The attachments show that pulseaudio was not running when the bug was reported in 2014. That's why things seem to disappear in the GUI:
!!Sound Servers on this system !!---------------------------- Pulseaudio: Installed - Yes (/usr/bin/pulseaudio) Running - No Please let us know if you still experience the problem, and if so then in what Ubuntu version. ** Changed in: pulseaudio (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1336274 Title: HDMI Audio and all other audio disappeared from input sources and output sources in the audio control panel and stereo system is looping between audio is coming and audio is not coming from the computer. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/pulseaudio/+bug/1336274/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs