Rocksmith 2014 not working anymore

[Duesenberger]

I have a problem with Rocksmith 2014. It is not working anymore on my pc.
When I try to launch it via Steam, it tries to start, but then I am back in Steam.

Here is a video of what happens, when I try to launch the game:

I already un-installed and re-installed. I used the old version, too, which is available via switch. And I validated the games files.
There is no valid Rocksmith settings file after re-installation in the game directory.
Will this be created during first start of the game?
What can cause this behaviour?

I used RSDiag, too, and it does not find the game directory automatically, I have to select it. And the diag-file is very short:

 

Rocksmith Location: O:\SteamLibrary\steamapps\common\Rocksmith2014
Valid CDLC DLL: False
DLL Type: None
Valid Game: False

Potential Red Flags: