Have a similar issue with my HP Pavilion DV6 Laptop under both Ubuntu
16.04 and Ubuntu Mate 16.04 using pulse audio.
Video still displays out of HDMI port to TV but Audio hardware device
disappears from sound applet (in my case "mate-volume-control-applet").
Curiously the HDMI device is visible
Yes I have the same issue* using Ubuntu 15.10 Flashback (Compiz).
* The Alt-F1 key does not open the (Applications) main menu.
Your work-around (below) did fix the problem for me though: -
$ grep -r "'s'" /usr/share/glib-2.0/schemas
# backup this file
$ sudo cp
