Prefab is "forgetting" public variables on instantiation

Unity Engine
1

Hello, I have a problem where I can’t find a solution:

I’m adding objects to a list on a script on a prefab with this code:

        if (UnityEditor.Experimental.SceneManagement.PrefabStageUtility.GetCurrentPrefabStage() != null) // In Prefab Mode
        {
            RoomConfig currentConfig = UnityEditor.Experimental.SceneManagement.PrefabStageUtility.GetCurrentPrefabStage().FindComponentOfType<RoomConfig>();
            string path = UnityEditor.Experimental.SceneManagement.PrefabStageUtility.GetPrefabStage(Selection.activeObject as
                 GameObject).assetPath; // Get the prefab path in disk
            GameObject prefabRoot = PrefabUtility.LoadPrefabContents(path); // Load the contents of the prefab.
            SerializedObject saveConfig = new SerializedObject(currentConfig);
            currentConfig.AddPositionMarker(this); // Add a reference to this object to the RoomConfig

            saveConfig.Update();
            saveConfig.ApplyModifiedProperties();// Apply after editing so that the values are stored

            try
            {
                PrefabUtility.SaveAsPrefabAsset(prefabRoot, path); // Save the prefab to disk    
                Debug.Log("Saving prefab");
            }
             finally
            {
                PrefabUtility.UnloadPrefabContents(prefabRoot);     // Unload to clear memory..              
            }
        }
        else
        {
            RoomConfig currentConfig = FindObjectOfType<RoomConfig>();
            currentConfig.AddPositionMarker(this);
            EditorUtility.SetDirty(currentConfig);
        }

Now this works fine in the Prefab Editor. I can see the added reference in the public field of the RoomConfig. (Yes I made sure it’s public and gets saved ^^)

However when I instatiate the Prefab during Runtime I have this weird behaviour:
It works the first time just fine. But when I start the Scene a second time the Prefab loses the added references.

When I drag the prefab into the current scene the added fields get automatically flagged as “changed” by the Editor. (Bold font and listed in the override list).

What am I doing wrong? Or is it a bug?

2

Ok, found the answer myself. I needed to add the “EditorUtility.SetDirty” also to the Prefab Editor branch.