Can't install or play any PC Game Pass game 0x80004005 / 0x00000001 / Sad Face

For almost two weeks now I have the issue that I can neither install a PC Game Pass game on my Windows 10 PC (local administrator account).

Previously I had dozens of Game Pass games installed and they all worked fine.

Symptoms:

• It all started almost two week ago when I was still able to launch Forza Horizon 5 (Game Pass), but noticed all online components in the game were greyed out. After that I restarted the PC and the game and since then I can't even launch the game or any other game pass game anymore.
  
• Trying to launch an installed Game Pass game gives error 0x80004005
  
• Trying to install a Game Pass game (with the Xbox app) that was previously installed also gives error 0x80004005 before it starts downloading
  
• Trying to install a Game Pass game that has never been installed on this PC gives error 0x00000001 before it starts downloading
  
• After I have run into the above described errors trying to install Game Pass games, the Xbox app will then show the "sad face" icon instead of the "Install" button for every Game Pass game that I haven't had installed before, until I reset the Xbox app (I still see the "Install" button for all Game Pass games that have previously been installed, but of course any attempt of actually installing ends with error 0x80004005)
  
• I can download, install and play any games that are in my library and that I own just fine (e.g. Forza Horizon 4), but none that are on Game Pass.
  

I have tried pretty much all that I could find online and more, except resetting/reinstalling Windows (unacceptable as a solution due to the required time having to reinstall and reconfigure/customize probably 100 programs on the PC, so that is simply a no go):

• Search for updates (everything is up to date)
  
• Reset Xbox app
  
• Reset Store
  
• Store troubleshooter
  
• Disable/enable IPv6
  
• Reinstall Gaming Services via PowerShell
  
• The usual DSIM and SFC commands (nothing was ever found)
  
• Updating to Windows 11
  
• Going back to Windows 10
  
• Taking ownership of the WindowsApps folder and deleting it completely and then reinstalling Store and Apps via PowerShell
  

What does work on the very same PC however is installing and playing any Game Pass games when I am logged in to Windows 10 with a newly created, secondary administrator account. This also is not a long term solution however, I simply can't disconnect my main user session each time I want to play a game. Neither is it an option of transferring all programs, configurations and customizations of dozens of programs to the secondary account.

Other infos:

• I am a Game Pass Ultimate subscriber and the subscription is valid.
  
• Installing and launching owned Windows Store/Xbox games still works on the main account
  
• Installing and launching games from any other service like Steam or Epic works on the main account as well
  

I would really appreciate a solution that doesn't involve resetting or reinstalling my PC or having to switch to a secondary user account in Windows every time I want to play a Game Pass game.

There must be some reason and solution to why no Game Pass games will run on my main local Windows account.

:)