On Linux on versions 4.12.4 and 4.13.0, I have to manually re-select the audio output device under Settings → Playback → Audio Output by switching to another device and back again, even though it’s already set, otherwise music won’t play (the progress bar for the song doesn’t move even though the song is indicated as playing).
I have the same issue, using 4.12.4 with Ubuntu 24.04.3 on amd64. It started with the .appimage version. When I deleted the appimage, and installed the flatpak version of 4.12.4, the problem did not happen on the first play - after logging in. However, after closing the app and re-opening it the problem returned. So, I can attest that this is a problem for both appimage and flatpak. I’m not going to try the snap - been burned too many times with Plexamp using that format.
If it helps, I tried several computers. Another Ubuntu 24.04.3 worked just fine with 4.12.4. As did a different one with Ubuntu 25.10. However a third one running Ubuntu 25.10 also has this issue. (all of these ran flatpak versions) Lastly, a Win11 PC with 4.12.3 also had no problems.