It's great that you showed the videos...
it seems to me that it maybe the driver at fault.
After watching the last video, I suspect three possible errors.
Normally, this is how the whole process should run:
But in your case the steam interface starts properly.
I see something only one difference, that the VR interface shows a mirroring display by default.
It might be something from the SteamVR apps.
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Please check which applications are enabled in the VR interface:
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As you see I also use several tools.
And it happens that the error is because of this.
Maybe try turning off unnecessary VR devices. Or turn it on if SteamVR just turned it off automatically.
when I have serious error in VR.
I always check the integrity of the files first! Unfortunately, it often happens that the updates are installed incorrectly.
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This has solved the error for me several times.
Another strange thing is that the screen is black. I mean in the game too not only in the vr view.
Maybe the videocard driver should be updated?! You should try a "clean install"
I think they could be all possible sources of error.
Another potential error:
Maybe you use some kind of mod in the heat game?!
I think not. But it may happen that there is no compatibility between the versions.
I also suspect this because this is the only place where the error occurs.
If this is also the case with other Unity games, then it is clearly a driver error.