Steam VR Prefabs lose references sometimes

[manuelgoellnitz]

I am using SteamVR with Unity 2021.2.0b14.

And at some point when working with the Interaction System demo scene, the References in SteamVR Prefabs is null. But I never touched them. And also there are no changes to that prefabs in our version control system. For example in all prefabs which have RenderModel.cs on them the reference to the hand prefab an the controller is gone.

reimporting the assets fixes that.

Any idea what could cause this? Only the steamVR preabs are affected. Not the ones of other plugins or the one we created for our project.