Games Running on Proton when OS & Games are installed onto a USB Stick

System Information

• GPU: RX 5600XT
• Driver/LLVM version: Mesa 23.0.3
• Kernel version: 6.1.37
• Link to full system information report as Gist:
• Proton version: Any, but report on 8.0-2d

Symptoms

Proton cannot load videos in game when the OS and Games are both installed on a USB Stick.

Reproduction

So far based on my testing, it's distro agnostic, wayland/x11 agnostic, and proton version agnostic, video filetype agnostic.

Games that are installed on a HDD and mounted to the USB stick play normally. Likewise, games that are installed on the USB but played on the HDD's OS also play fine.

Tested with both NixOS and Nobara on the USB stick.

While admittedly a niche issue, I did want to bring light to it as I've not seen any mention of such a bug, which isn't game specific as I learned after my initial report.

steam-367500.log

Originally posted by @RavingGrob in https://github.com/ValveSoftware/Proton/issues/1235#issuecomment-1624811787

Start by reviewing the attached steam-367500.log and the reported Proton version and system details. Reproduce the issue with both the operating system and game installed on a USB stick, compare it with the working HDD/USB arrangements, and consider the issue resolved when in-game videos play in the failing setup without regressing those working cases.