Proton fails to populate dosdevices

[Kimplul]

I have a separate ext4 drive that's exclusively for my games, but when I try to install games with Proton to it none of them launch, becuase pfx/dosdevices is empty. Any combination of game and proton version has so far failed to start without manually populating pfx/dosdevices with the expected symlinks. I have two library folders, one in the default .steam-location and the other on the second drive. Installing games to .steam works fine.

All games give error logs similar to this: https://gist.github.com/Kimplul/e8d7fb4dcb2119a9cf6e3893258b812c
And here's my system information: https://gist.github.com/Kimplul/9a5ccd79801550c45d1d2f8cbc0e38da

[devurandom]

I run into the same issue with an external drive that has a btrfs file system (and had the same problem when the drive was formatted as NTFS and I mounted it as the new ntfs3 Linux file system type).

I work around it by running rsync -avP ~/.var/app/com.valvesoftware.Steam/data/Steam/steamapps/compatdata/$WORKINGAPP_ID/pfx/dosdevices/ /run/media/$USER/$DRIVE/SteamLibrary/steamapps/compatdata/$BROKENAPP_ID/pfx/dosdevices/. After I have done that, the game's installer (vcredist & Co) runs. Everything apart from dosdevices appears to be created correctly.

Steam is installed as a Flatpak here, the external drive is made accessible via flatpak override --filesystem=/run/media/$USER/$DRIVE/ com.valvesoftware.Steam.

[devurandom]

I switched from NTFS to Btrfs in the meantime. That did not change anything about the behaviour mentioned above. (cf. #150 (comment)) I then switched to Proton 7.0-1, which appears to have resolved the problem.