On Thursday 24 May 2018 00:15:29 Jan Stolarek wrote:
> Starting a few days ago volume up/down buttons no longer work. They will
> change sound volume by 5% up/down but no more than that. They also don't
> trigger an OSD. Also, mute button now works normally - it mutes and unmutes
> sound without any need to manually unmute the channels. 

You changed the mixer.
On the applet > select Master channel
make sure "current mixer" is pulseaudio
This will revert you back where you where.
unmute broken, but working volume keys.