diff --git a/.github/workflows/build-msi-package.yml b/.github/workflows/build-msi-package.yml
index 66cb6cf7..5997c9c6 100644
--- a/.github/workflows/build-msi-package.yml
+++ b/.github/workflows/build-msi-package.yml
@@ -1,8 +1,8 @@
 on:
   push:
-    branches: [ master ]
+    branches: [ master,release_branch* ]
   pull_request:
-    branches: [ master ]
+    branches: [ master,release_branch* ]
   workflow_dispatch:
 
 permissions: read-all
diff --git a/.github/workflows/build-multi-static.yml b/.github/workflows/build-multi-static.yml
index c510c5cd..6a95e140 100644
--- a/.github/workflows/build-multi-static.yml
+++ b/.github/workflows/build-multi-static.yml
@@ -1,8 +1,8 @@
 on:
   push:
-    branches: [ master ]
+    branches: [ master,release_branch* ]
   pull_request:
-    branches: [ master ]
+    branches: [ master,release_branch* ]
   workflow_dispatch:
 
 permissions: read-all
diff --git a/.github/workflows/build-multi.yml b/.github/workflows/build-multi.yml
index 0921e8ad..e3bb075d 100644
--- a/.github/workflows/build-multi.yml
+++ b/.github/workflows/build-multi.yml
@@ -1,8 +1,8 @@
 on:
   push:
-    branches: [ master ]
+    branches: [ master,release_branch* ]
   pull_request:
-    branches: [ master ]
+    branches: [ master,release_branch* ]
   workflow_dispatch:
 
 permissions: read-all
diff --git a/.github/workflows/build-quick-static.yml b/.github/workflows/build-quick-static.yml
index 24a99d96..85f0302b 100644
--- a/.github/workflows/build-quick-static.yml
+++ b/.github/workflows/build-quick-static.yml
@@ -1,8 +1,8 @@
 on:
   push:
-    branches: [ master ]
+    branches: [ master,release_branch* ]
   pull_request:
-    branches: [ master ]
+    branches: [ master,release_branch* ]
   workflow_dispatch:
 
 permissions: read-all
diff --git a/.github/workflows/build-quick.yml b/.github/workflows/build-quick.yml
index 8ffeba83..fbdb2c02 100644
--- a/.github/workflows/build-quick.yml
+++ b/.github/workflows/build-quick.yml
@@ -1,8 +1,8 @@
 on:
   push:
-    branches: [ master ]
+    branches: [ master,release_branch* ]
   pull_request:
-    branches: [ master ]
+    branches: [ master,release_branch* ]
   workflow_dispatch:
 
 permissions: read-all
diff --git a/CHANGELOG.md b/CHANGELOG.md
index aab11a01..0baad0e2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,8 @@
 # Level zero loader changelog
 
+
+## v1.21.10
+* Block all calls to get until after init has completed to avoid race during sorting.
 ## v1.21.9
 * Fix init checks when sorting legacy drivers
 * Fix MSVC Link optimization flags
diff --git a/CMakeLists.txt b/CMakeLists.txt
index b2114c34..39f4fd7f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -13,7 +13,7 @@ if(MSVC AND (MSVC_VERSION LESS 1900))
 endif()
 
 # This project follows semantic versioning (https://semver.org/)
-project(level-zero VERSION 1.21.9)
+project(level-zero VERSION 1.21.10)
 
 include(GNUInstallDirs)
 
diff --git a/PRODUCT_GUID.txt b/PRODUCT_GUID.txt
index 85c64204..852e6593 100644
--- a/PRODUCT_GUID.txt
+++ b/PRODUCT_GUID.txt
@@ -1,2 +1,2 @@
-1.21.9
-01037281-c9ef-43cf-bc65-f72fb3438788
\ No newline at end of file
+1.21.10
+98f4ce5b-d498-4ec9-b025-2e509c4ebecc
\ No newline at end of file
diff --git a/scripts/templates/ldrddi.cpp.mako b/scripts/templates/ldrddi.cpp.mako
index 9381c3c2..c507a123 100644
--- a/scripts/templates/ldrddi.cpp.mako
+++ b/scripts/templates/ldrddi.cpp.mako
@@ -79,23 +79,26 @@ namespace loader
         %elif re.match(r"\w+DriverGet$", th.make_func_name(n, tags, obj)) or re.match(r"\w+InitDrivers$", th.make_func_name(n, tags, obj)):
         uint32_t total_driver_handle_count = 0;
 
-        if (!loader::context->sortingInProgress.exchange(true) && !loader::context->instrumentationEnabled) {
-            %if namespace != "zes":
-            %if not re.match(r"\w+InitDrivers$", th.make_func_name(n, tags, obj)):
-            std::call_once(loader::context->coreDriverSortOnce, []() {
-                loader::context->driverSorting(&loader::context->zeDrivers, nullptr, false);
-            });
-            %else:
-            std::call_once(loader::context->coreDriverSortOnce, [desc]() {
-                loader::context->driverSorting(&loader::context->zeDrivers, desc, false);
-            });
-            %endif
-            %else:
-            std::call_once(loader::context->sysmanDriverSortOnce, []() {
-                loader::context->driverSorting(loader::context->sysmanInstanceDrivers, nullptr, true);
-            });
-            %endif
-            loader::context->sortingInProgress.store(false);
+        {
+            std::lock_guard<std::mutex> lock(loader::context->sortMutex);
+            if (!loader::context->sortingInProgress.exchange(true) && !loader::context->instrumentationEnabled) {
+                %if namespace != "zes":
+                %if not re.match(r"\w+InitDrivers$", th.make_func_name(n, tags, obj)):
+                std::call_once(loader::context->coreDriverSortOnce, []() {
+                    loader::context->driverSorting(&loader::context->zeDrivers, nullptr, false);
+                });
+                %else:
+                std::call_once(loader::context->coreDriverSortOnce, [desc]() {
+                    loader::context->driverSorting(&loader::context->zeDrivers, desc, false);
+                });
+                %endif
+                %else:
+                std::call_once(loader::context->sysmanDriverSortOnce, []() {
+                    loader::context->driverSorting(loader::context->sysmanInstanceDrivers, nullptr, true);
+                });
+                %endif
+                loader::context->sortingInProgress.store(false);
+            }
         }
 
         %if namespace != "zes":
diff --git a/scripts/templates/ze_loader_internal.h.mako b/scripts/templates/ze_loader_internal.h.mako
index 9937b814..b86c1c9a 100644
--- a/scripts/templates/ze_loader_internal.h.mako
+++ b/scripts/templates/ze_loader_internal.h.mako
@@ -121,6 +121,7 @@ namespace loader
         std::once_flag coreDriverSortOnce;
         std::once_flag sysmanDriverSortOnce;
         std::atomic<bool> sortingInProgress = {false};
+        std::mutex sortMutex;
         bool instrumentationEnabled = false;
         dditable_t tracing_dditable = {};
         std::shared_ptr<Logger> zel_logger;
diff --git a/source/loader/ze_ldrddi.cpp b/source/loader/ze_ldrddi.cpp
index 8d080a5c..a9f64c0c 100644
--- a/source/loader/ze_ldrddi.cpp
+++ b/source/loader/ze_ldrddi.cpp
@@ -56,11 +56,14 @@ namespace loader
 
         uint32_t total_driver_handle_count = 0;
 
-        if (!loader::context->sortingInProgress.exchange(true) && !loader::context->instrumentationEnabled) {
-            std::call_once(loader::context->coreDriverSortOnce, []() {
-                loader::context->driverSorting(&loader::context->zeDrivers, nullptr, false);
-            });
-            loader::context->sortingInProgress.store(false);
+        {
+            std::lock_guard<std::mutex> lock(loader::context->sortMutex);
+            if (!loader::context->sortingInProgress.exchange(true) && !loader::context->instrumentationEnabled) {
+                std::call_once(loader::context->coreDriverSortOnce, []() {
+                    loader::context->driverSorting(&loader::context->zeDrivers, nullptr, false);
+                });
+                loader::context->sortingInProgress.store(false);
+            }
         }
 
         for( auto& drv : loader::context->zeDrivers )
@@ -138,12 +141,14 @@ namespace loader
         ze_result_t result = ZE_RESULT_SUCCESS;
 
         uint32_t total_driver_handle_count = 0;
-
-        if (!loader::context->sortingInProgress.exchange(true) && !loader::context->instrumentationEnabled) {
-            std::call_once(loader::context->coreDriverSortOnce, [desc]() {
-                loader::context->driverSorting(&loader::context->zeDrivers, desc, false);
-            });
-            loader::context->sortingInProgress.store(false);
+        {
+            std::lock_guard<std::mutex> lock(loader::context->sortMutex);
+            if (!loader::context->sortingInProgress.exchange(true) && !loader::context->instrumentationEnabled) {
+                std::call_once(loader::context->coreDriverSortOnce, [desc]() {
+                    loader::context->driverSorting(&loader::context->zeDrivers, desc, false);
+                });
+                loader::context->sortingInProgress.store(false);
+            }
         }
 
         for( auto& drv : loader::context->zeDrivers )
diff --git a/source/loader/ze_loader_internal.h b/source/loader/ze_loader_internal.h
index 295a33a2..1de27195 100644
--- a/source/loader/ze_loader_internal.h
+++ b/source/loader/ze_loader_internal.h
@@ -155,6 +155,7 @@ namespace loader
         std::once_flag coreDriverSortOnce;
         std::once_flag sysmanDriverSortOnce;
         std::atomic<bool> sortingInProgress = {false};
+        std::mutex sortMutex;
         bool instrumentationEnabled = false;
         dditable_t tracing_dditable = {};
         std::shared_ptr<Logger> zel_logger;
diff --git a/source/loader/zes_ldrddi.cpp b/source/loader/zes_ldrddi.cpp
index 0edb0846..0785c5c5 100644
--- a/source/loader/zes_ldrddi.cpp
+++ b/source/loader/zes_ldrddi.cpp
@@ -60,11 +60,14 @@ namespace loader
 
         uint32_t total_driver_handle_count = 0;
 
-        if (!loader::context->sortingInProgress.exchange(true) && !loader::context->instrumentationEnabled) {
-            std::call_once(loader::context->sysmanDriverSortOnce, []() {
-                loader::context->driverSorting(loader::context->sysmanInstanceDrivers, nullptr, true);
-            });
-            loader::context->sortingInProgress.store(false);
+        {
+            std::lock_guard<std::mutex> lock(loader::context->sortMutex);
+            if (!loader::context->sortingInProgress.exchange(true) && !loader::context->instrumentationEnabled) {
+                std::call_once(loader::context->sysmanDriverSortOnce, []() {
+                    loader::context->driverSorting(loader::context->sysmanInstanceDrivers, nullptr, true);
+                });
+                loader::context->sortingInProgress.store(false);
+            }
         }
 
         for( auto& drv : *loader::context->sysmanInstanceDrivers )