I am experiencing this issue on Ubuntu 22.04 with Plexamp AppImage 4.2.2.
./Plexamp-422.AppImage
Main: Window state x:undefined y:undefined w:270 h:515 fullscreen:undefined maximized:undefined
Main: Display bounds x:undefined y:undefined w:undefined h:undefined
Started Media Service: false
Linux: Registering MPRIS service.
libva error: vaGetDriverNameByIndex() failed with unknown libva error, driver_name = (null)
libva error: vaGetDriverNameByIndex() failed with unknown libva error, driver_name = (null)
libva error: vaGetDriverNameByIndex() failed with unknown libva error, driver_name = (null)
[85391:0614/182910.465236:FATAL:gpu_data_manager_impl_private.cc(415)] GPU process isn’t usable. Goodbye.