Same problem for me. I solved it by:
1. Open up the Volume Control (gnome-volume-control).
2. Click 'Preferences'. Enable Surround, Center, LFE, Side. Click Close.
3. Set Surround, Center, LFE, Side. Click Close to 100%.
The bug (for me) really is Surround, Center, LFE, Side should be 100% by default.
Same problem for me. I solved it by: volume- control) .
1. Open up the Volume Control (gnome-
2. Click 'Preferences'. Enable Surround, Center, LFE, Side. Click Close.
3. Set Surround, Center, LFE, Side. Click Close to 100%.
The bug (for me) really is Surround, Center, LFE, Side should be 100% by default.