-e: when you have the player prefab highlighted in the inspector and then start the scene the action map reference vanishes from the component
--repros with 1.0-preview 5 and 6, downgrading down to preview4 doesn't show the issue, but throws errors

-repro:
--open Demo1 scene
--in the Project View > _Prefabs select the PlayerPrefab
--scroll down to the Player Input component
--start the play mode
--NOTICE the "My Actions" action map reference vanishes from the inspector