Sounds like you’ve tried some different formatted partitions for the os, have you done the same for the games too? When I switched from Windows to dual-boot Linux I kept my existing NTFS partition for games, those games shows up as installed in Steam but wouldn’t launch properly.
If that doesn’t help, add this to your game’s launch options to get a log which should include an error:
Sounds like you’ve tried some different formatted partitions for the os, have you done the same for the games too? When I switched from Windows to dual-boot Linux I kept my existing NTFS partition for games, those games shows up as installed in Steam but wouldn’t launch properly.
If that doesn’t help, add this to your game’s launch options to get a log which should include an error:
PROTON_LOG=1 %command%Log should be in your home directory.