We are using the standard Unity 5.5.0f3. We have a consistent problem. If a user creates a new prefab and adds it as a reference on an existing prefab, all other users, when they update, see that new reference as null. For example I have an existing prefab A with MonoBehaviour MyComponentA. To this component I add "public Transform theOtherThing;" I then create new prefab "OtherThingB" and drag it, in the Project view, to "theOtherThing" field of MyComponentA. It's definitely applied to the prefab, not an instance of the prefab in a scene. Submit changes. Another user updates. They get the new prefab OtherThingB, but the theOtherThing field in prefab MyComponentA is null. It should be a reference to OtherThingB. Is this a known issue or are we doing something wrong? Thanks.