Flush meta cache after delete.

Author: peterwilsoncc

src/wp-includes/collaboration/class-wp-sync-post-meta-storage.php

@@ -302,6 +302,7 @@ public function remove_updates_before_cursor( string $room, int $cursor ): bool
 			return false;
 		}
 
+		wp_cache_maybe_set_posts_last_changed_following_post_meta_update( array(), $post_id, self::SYNC_UPDATE_META_KEY );
 		return true;
 	}
 }