The system won’t find any audio devices after the user logs off and back on. Sound cards are only recognized on the first session after the system has booted. Steps to reproduce:
1 - Power on your computer and login to your user account. You should see all your sound devices listed and applications playing audio.
2 - Log out and wait to be taken back to the login manager.
3 - Log back in to the same account. Sound is now disabled and all applications are unable to find any audio cards.
I use openSUSE Tumbleweed x64 with the KDE Desktop.
Thanks. My report got marked as a duplicate of that one, so I’ll be following it. Comments there suggest that restarting Pulseaudio should work, and since I don’t normally need to log out and back in anyway, a workaround shouldn’t be a problem.