Fix issue #1246

Author: HuJK

core/src/main/java/com/github/games647/fastlogin/core/shared/FloodgateManagement.java

@@ -167,6 +167,13 @@ public void run() {
             return;
         }
 
+        // Set the UUID for the player login from floodgate.
+        if (isLinked && profile.isOnlinemodePreferred()) {
+            profile.setId(floodgatePlayer.getCorrectUniqueId());
+            core.getPlugin().getLog().info(
+                "Player {} login as a Floodgate linked premium user (UUID: {})",
+                username, floodgatePlayer.getCorrectUniqueId());
+        }
         //start Bukkit/Bungee specific tasks
         startLogin();
 

core/src/main/java/com/github/games647/fastlogin/core/shared/ForceLoginManagement.java

@@ -80,7 +80,13 @@ public void run() {
                     if (success) {
                         //update only on success to prevent corrupt data
                         if (playerProfile != null) {
-                            playerProfile.setId(session.getUuid());
+                            if (session.getUuid() == null) {
+                                // Set session ID from floodgatePlayer.getCorrectUniqueId()
+                                session.setUuid(playerProfile.getId());
+                            } else {
+                                // Set player UUID to session UUID
+                                playerProfile.setId(session.getUuid());
+                            }
                             playerProfile.setOnlinemodePreferred(true);
                             storage.save(playerProfile);
                         }