@SteenLund @LeonhardP @runevision Hi all - I'm not sure if our problems are directly related to the projects that have been shared here in the thread, but Unity 2019.1 and 2019.2 (currently we're using 2019.2.9f1 on Mac) have been absolutely terrible maintaining references in scenes, prefabs, scriptable objects, etc. in our project. We play and stop in the Editor, references randomly get lost. We edit prefabs, references randomly get lost. ScriptableObjects we're using for configuration lose their references to prefabs. Prefabs, nested prefabs, and prefab variants periodically lose all sorts of references to themselves, their parents, their overrides, etc. Materials fall off MeshRenderers randomly during editing or after returning from play mode. Sometimes after stopping play mode, game objects that were loaded during play mode into the 'DontDestroyOnLoad' scene end up in the scene that is open for editing and then saved along with any other changes that might be made. We cannot file bug useful reports because we cannot replicate these issues reliably so I'm not sure how best to communicate the problem. We've talked to quite a few other developers and a few plugin authors this year and they all seem to agree that Unity serialisation has been quite brittle this year, with prefabs and lost references being a particular problem. We have written editor tools to try to flush Scriptable Objects so they can be reloaded when they lose references. Almost always the data on disk is fine, so it seems to be something happening to loaded assets with lost references. Prefabs are trickier, but eventually unloading, loading, quitting, reloading the editor, reimporting the prefab or scene assets, or outright deleting the Library folder and reimporting everything gets things going again. This is obviously a big problem and a massive timesink for us. A quick search of the issues, forums, answers, etc. shows that there have been quite a few 'missing reference' type issues raised over the last year. Is Unity aware of any ongoing serialisation and reference errors with scenes, prefabs, scriptable objects, etc? Are there any fixes in progress at the moment that we can we expect to improve things any time soon? Thanks for any response and suggestions you can offer.