Here's a list of known issues to be aware of. (Minor and cosmetic bugs are not listed.) We will keep the list updated. [FIXED] Missing references and incorrect values when Prefabs have scripts that don't compile There is a known issue that causes Prefab instance property values to be wrong. This includes broken references. The issue appears if there are scripts that have compile errors when Prefabs are imported. The current workaround is to fix script errors and then do a reimport. Either reimport the affected Prefabs or do a Reimport All. [FIXED] Prefab Mode in Play Mode may cause physics issues If you edit a Prefab with Rigidbodies, colliders, or other Physics components on it (2D or 3D) in Prefab Mode, and you go into Play Mode, the Prefab may incorrectly affect the gameplay of the game in Play Mode, or the Prefab may incorrectly be modified by Play Mode physics simulation and have those modifications stay. There is a planned fix to this which is not part of the Preview build.