diff --git a/bin/scripts/fix-data/fix_missing_custom_user_props.js b/bin/scripts/fix-data/fix_missing_custom_user_props.js
new file mode 100644
index 00000000000..73c8a35729b
--- /dev/null
+++ b/bin/scripts/fix-data/fix_missing_custom_user_props.js
@@ -0,0 +1,379 @@
+/**
+ *  Description: This script fixes missing custom user properties in drill_meta
+ *  or adds new values to existing biglist properties.
+ *  It scans the app_users collection for the specified custom properties and
+ *  ensures they are present in drill_meta with correct types and values.
+ *  Path: $(countly dir)/bin/scripts/fix-data
+ *  Command: node fix_missing_custom_user_props.js
+ */
+
+const pluginManager = require('../../../plugins/pluginManager.js');
+
+const APP_ID = ""; // required: set the app ID to process
+const PROPS = []; // required: specify custom property names to fix, e.g. ["myProp1", "myProp2"]
+const START = new Date(Date.now() - 30 * 24 * 60 * 60 * 1000); // default: 30 days ago
+const END = new Date(); // default: now
+const dry_run = true;
+
+let LIST_LIMIT = 100;
+let BIG_LIST_LIMIT = 1000;
+
+if (!APP_ID) {
+    console.error("Error: APP_ID is required. Please set it in the script.");
+    process.exit(1);
+}
+
+if (!PROPS.length) {
+    console.error("Error: PROPS is required. Please specify at least one property name to fix.");
+    process.exit(1);
+}
+
+Promise.all([
+    pluginManager.dbConnection("countly"),
+    pluginManager.dbConnection("countly_drill")
+]).then(async function([countlyDb, drillDb]) {
+    console.log("Connected to databases...");
+    console.log("Date range: " + START.toISOString() + " - " + END.toISOString());
+    console.log("Properties to fix: " + PROPS.join(", "));
+
+    var lacStart = Math.round(START.getTime() / 1000);
+    var lacEnd = Math.round(END.getTime() / 1000);
+    var lacMatch = {$gt: lacStart, $lt: lacEnd};
+    var collection = "app_users" + APP_ID;
+
+    try {
+        // Load drill config limits from the database if available
+        var pluginsDoc = await countlyDb.collection("plugins").findOne({_id: "plugins"});
+        if (pluginsDoc && pluginsDoc.drill) {
+            if (pluginsDoc.drill.list_limit !== undefined) {
+                LIST_LIMIT = parseInt(pluginsDoc.drill.list_limit, 10) || LIST_LIMIT;
+            }
+            if (pluginsDoc.drill.big_list_limit !== undefined) {
+                BIG_LIST_LIMIT = parseInt(pluginsDoc.drill.big_list_limit, 10) || BIG_LIST_LIMIT;
+            }
+        }
+        console.log("Limits: list_limit=" + LIST_LIMIT + ", big_list_limit=" + BIG_LIST_LIMIT);
+
+        // Get existing drill_meta for user properties
+        var metaDoc = await drillDb
+            .collection("drill_meta")
+            .findOne({_id: APP_ID + "_meta_up"});
+        var existingCustom = (metaDoc && metaDoc.custom) ? metaDoc.custom : {};
+        console.log("Existing custom keys in drill_meta: " + Object.keys(existingCustom).length);
+
+        // Load existing biglist documents for the requested props
+        var existingBigLists = {};
+        for (var p = 0; p < PROPS.length; p++) {
+            var bigListId = APP_ID + "_meta_up_custom." + encodeKey(PROPS[p]);
+            var bigListDoc = await drillDb.collection("drill_meta").findOne({_id: bigListId});
+            if (bigListDoc && bigListDoc.values) {
+                existingBigLists[PROPS[p]] = bigListDoc.values;
+            }
+        }
+
+        // Process each property
+        var mainDocUpdate = {};
+        var bigListUpdates = [];
+        var bigListCreates = [];
+
+        for (var pi = 0; pi < PROPS.length; pi++) {
+            var prop = PROPS[pi];
+            var fieldPath = "custom." + prop;
+            var existingMeta = existingCustom[prop];
+
+            console.log("[" + (pi + 1) + "/" + PROPS.length + "] Processing \"" + prop + "\"...");
+
+            // If property already exists and is not a list type, skip entirely
+            if (existingMeta && existingMeta.type !== "l" && existingMeta.type !== "a" && existingMeta.type !== "bl") {
+                console.log("  [SKIP] Already exists with type: " + existingMeta.type + " (not a list type, nothing to update)");
+                continue;
+            }
+
+            if (!existingMeta) {
+                // New property — determine type from a small sample first
+                var samples = await countlyDb.collection(collection).aggregate([
+                    {$match: {lac: lacMatch, [fieldPath]: {$exists: true}}},
+                    {$project: {_id: 0, val: "$" + fieldPath}},
+                    {$limit: 100}
+                ]).toArray();
+
+                if (samples.length === 0) {
+                    console.log("  No users with this property in the given date range.");
+                    continue;
+                }
+
+                var isArray = samples.some(function(s) {
+                    return Array.isArray(s.val);
+                });
+                var sampleValues = [];
+                for (var si = 0; si < samples.length; si++) {
+                    if (Array.isArray(samples[si].val)) {
+                        for (var ai = 0; ai < samples[si].val.length; ai++) {
+                            sampleValues.push(samples[si].val[ai] + "");
+                        }
+                    }
+                    else {
+                        sampleValues.push(samples[si].val + "");
+                    }
+                }
+
+                var type = determineType(sampleValues, isArray);
+
+                if (type === "n" || type === "d") {
+                    console.log("  [NEW] type: " + type + " (determined from " + samples.length + " samples, no values to collect)");
+                    mainDocUpdate["custom." + prop + ".type"] = type;
+                    continue;
+                }
+
+                // List/array type — need full distinct values aggregation
+                console.log("  [NEW] type: " + type + ", collecting distinct values...");
+                var distinctValues = await aggregateDistinctValues(countlyDb, collection, fieldPath, lacMatch, isArray);
+                var totalDistinct = Object.keys(distinctValues).length;
+                console.log("  Found " + totalDistinct + " distinct value(s)");
+
+                // Apply limits
+                if (totalDistinct > BIG_LIST_LIMIT) {
+                    // Too many values — convert to string type, no values tracked
+                    console.log("  [WARNING] " + totalDistinct + " values exceeds big_list_limit (" + BIG_LIST_LIMIT + "). Setting type to 's' (string). Values will not be tracked.");
+                    mainDocUpdate["custom." + prop + ".type"] = "s";
+                    continue;
+                }
+
+                if (totalDistinct > LIST_LIMIT) {
+                    // Between list_limit and big_list_limit — use bl type
+                    console.log("  [INFO] " + totalDistinct + " values exceeds list_limit (" + LIST_LIMIT + "). Setting type to 'bl' (big list) instead of '" + type + "'.");
+                    type = "bl";
+                }
+
+                mainDocUpdate["custom." + prop + ".type"] = type;
+
+                var createValues = {};
+                for (var cv in distinctValues) {
+                    var enc = encodeKey(cv).trim();
+                    if (enc !== "") {
+                        createValues[enc] = true;
+                    }
+                }
+                bigListCreates.push({
+                    _id: APP_ID + "_meta_up_custom." + encodeKey(prop),
+                    app_id: APP_ID,
+                    type: "up",
+                    e: "custom",
+                    biglist: true,
+                    values: createValues
+                });
+            }
+            else {
+                // Existing list type — collect distinct values and find new ones
+                console.log("  Existing type: " + existingMeta.type + ", collecting distinct values...");
+
+                var isArrayExisting = existingMeta.type === "a";
+                var distinctValuesExisting = await aggregateDistinctValues(countlyDb, collection, fieldPath, lacMatch, isArrayExisting);
+                var existingValues = existingBigLists[prop] || {};
+                var existingCount = Object.keys(existingValues).length;
+
+                var newValues = {};
+                for (var dv in distinctValuesExisting) {
+                    var enc2 = encodeKey(dv).trim();
+                    if (enc2 !== "" && !existingValues[enc2]) {
+                        newValues[enc2] = true;
+                    }
+                }
+
+                var newCount = Object.keys(newValues).length;
+                if (newCount === 0) {
+                    console.log("  [SKIP] No new values (all " + Object.keys(distinctValuesExisting).length + " already in biglist)");
+                    continue;
+                }
+
+                var totalAfterUpdate = existingCount + newCount;
+
+                // Check if adding new values would exceed big_list_limit
+                if (totalAfterUpdate > BIG_LIST_LIMIT) {
+                    console.log("  [WARNING] Adding " + newCount + " new values would bring total to " + totalAfterUpdate + ", exceeding big_list_limit (" + BIG_LIST_LIMIT + "). Converting type to 's' (string). Values will no longer be tracked.");
+                    mainDocUpdate["custom." + prop + ".type"] = "s";
+                    // Don't add values — the biglist doc will become stale but that's consistent
+                    // with how drill.js handles this (checkListsInMeta deletes it later)
+                    continue;
+                }
+
+                // Check if adding new values would cross the list_limit threshold (l -> bl)
+                if (existingMeta.type === "l" && totalAfterUpdate > LIST_LIMIT) {
+                    console.log("  [INFO] Adding " + newCount + " new values would bring total to " + totalAfterUpdate + ", exceeding list_limit (" + LIST_LIMIT + "). Upgrading type from 'l' to 'bl' (big list).");
+                    mainDocUpdate["custom." + prop + ".type"] = "bl";
+                }
+
+                console.log("  [UPDATE] " + newCount + " new value(s) to add (existing: " + existingCount + ", after: " + totalAfterUpdate + ")");
+                bigListUpdates.push({
+                    id: APP_ID + "_meta_up_custom." + encodeKey(prop),
+                    propKey: prop,
+                    newValues: newValues
+                });
+            }
+        }
+
+        // Check if there's anything to do
+        if (Object.keys(mainDocUpdate).length === 0 && bigListCreates.length === 0 && bigListUpdates.length === 0) {
+            console.log("\nNothing to update.");
+            return;
+        }
+
+        if (dry_run) {
+            if (Object.keys(mainDocUpdate).length > 0) {
+                console.log("\nDRY RUN: Would update main meta document (" + APP_ID + "_meta_up) with:");
+                console.log(JSON.stringify(mainDocUpdate, null, 2));
+            }
+            if (bigListCreates.length > 0) {
+                console.log("DRY RUN: Would create " + bigListCreates.length + " biglist document(s):");
+                for (var b = 0; b < bigListCreates.length; b++) {
+                    console.log("  _id: " + bigListCreates[b]._id + " (" + Object.keys(bigListCreates[b].values).length + " values)");
+                }
+            }
+            if (bigListUpdates.length > 0) {
+                console.log("DRY RUN: Would update " + bigListUpdates.length + " existing biglist document(s):");
+                for (var u = 0; u < bigListUpdates.length; u++) {
+                    console.log("  _id: " + bigListUpdates[u].id + " (+" + Object.keys(bigListUpdates[u].newValues).length + " new values)");
+                }
+            }
+        }
+        else {
+            // Update main meta_up document for new properties
+            if (Object.keys(mainDocUpdate).length > 0) {
+                await drillDb.collection("drill_meta").updateOne(
+                    {_id: APP_ID + "_meta_up"},
+                    {$set: mainDocUpdate},
+                    {upsert: true}
+                );
+                console.log("Updated main meta document.");
+            }
+
+            var bulk = null;
+
+            // Create new biglist documents
+            for (var b2 = 0; b2 < bigListCreates.length; b2++) {
+                if (!bulk) {
+                    bulk = drillDb.collection("drill_meta").initializeUnorderedBulkOp();
+                }
+                var doc = bigListCreates[b2];
+                var docId = doc._id;
+                delete doc._id;
+                bulk.find({_id: docId}).upsert().updateOne({$set: doc});
+            }
+
+            // Update existing biglist documents with new values
+            for (var u2 = 0; u2 < bigListUpdates.length; u2++) {
+                if (!bulk) {
+                    bulk = drillDb.collection("drill_meta").initializeUnorderedBulkOp();
+                }
+                var setObj = {};
+                var nv = bigListUpdates[u2].newValues;
+                for (var vk in nv) {
+                    setObj["values." + vk] = true;
+                }
+                bulk.find({_id: bigListUpdates[u2].id}).upsert().updateOne({$set: setObj});
+            }
+
+            if (bulk) {
+                await bulk.execute();
+                console.log("Executed " + (bigListCreates.length + bigListUpdates.length) + " biglist operation(s).");
+            }
+        }
+    }
+    catch (err) {
+        console.error("Error:", err);
+    }
+    finally {
+        countlyDb.close();
+        drillDb.close();
+        console.log("\nDone.");
+    }
+});
+
+/**
+ * Aggregate distinct values for a custom property using MongoDB aggregation
+ * @param {Db} db - database connection
+ * @param {string} collectionName - app_users collection name
+ * @param {string} fieldPath - dot-notation field path (e.g. "custom.myProp")
+ * @param {object} lacMatch - lac range filter ({$gt, $lt})
+ * @param {boolean} isArray - whether to unwind array values
+ * @returns {object} map of distinct values {value: true, ...}
+ */
+async function aggregateDistinctValues(db, collectionName, fieldPath, lacMatch, isArray) {
+    var pipeline = [
+        {$match: {lac: lacMatch, [fieldPath]: {$exists: true}}}
+    ];
+
+    if (isArray) {
+        pipeline.push({$unwind: {path: "$" + fieldPath, preserveNullAndEmptyArrays: false}});
+    }
+
+    pipeline.push({$group: {_id: "$" + fieldPath}});
+
+    var results = await db.collection(collectionName).aggregate(pipeline, {allowDiskUse: true}).toArray();
+    var values = {};
+    for (var i = 0; i < results.length; i++) {
+        if (results[i]._id !== null && results[i]._id !== undefined) {
+            values[results[i]._id + ""] = true;
+        }
+    }
+    return values;
+}
+
+/**
+ * Determine the type of a property based on its values
+ * Types: "n" (number), "d" (date), "l" (list/string), "a" (array)
+ * @param {string[]} values - array of string-encoded values
+ * @param {boolean} isArray - whether any user had this as an array value
+ * @returns {string} type code
+ */
+function determineType(values, isArray) {
+    if (isArray) {
+        return "a";
+    }
+
+    var isNumber = true;
+    var isDate = true;
+
+    for (var i = 0; i < values.length; i++) {
+        if (!isNumeric(values[i]) || values[i].length > 16) {
+            isNumber = false;
+            isDate = false;
+            break;
+        }
+        if (values[i].length !== 10 && values[i].length !== 13) {
+            isDate = false;
+        }
+    }
+
+    if (isNumber && isDate) {
+        return "d";
+    }
+    if (isNumber) {
+        return "n";
+    }
+    return "l";
+}
+
+/**
+ * Check if value is numeric
+ * @param {*} val - value to check
+ * @returns {boolean} true if numeric
+ */
+function isNumeric(val) {
+    if (typeof val === "number") {
+        return true;
+    }
+    if (typeof val === "string" && val.trim() !== "") {
+        return !isNaN(Number(val));
+    }
+    return false;
+}
+
+/**
+ * Encode key for MongoDB storage (replace $ and . characters)
+ * @param {string} key - key to encode
+ * @returns {string} encoded key
+ */
+function encodeKey(key) {
+    return (key + "").replace(/^\$/g, "&#36;").replace(/\./g, '&#46;');
+}