The logitech g933 (and similar headsets like g930, g633, ...) headset generally works on linux, but has a few bugs.
One of which is that sometimes the microphone gets stuck in mute. The hardware button has no effect.
It seems the headset somehow looses control of the mute control of the linux sound system. The issue seems to effect alsa, pulseaudio and jack2.
When that happens, what works for me is to unmute the audio with the following command:
amixer -c 1 sset Mic cap # on
amixer -c 1 sset Mic nocap # off
amixer -c 1 sset Mic toggle # toggle on/off
(-c 1 is to select the audio card and might be different for you. You might also need to specify a device with -D)
(For some users it might be possible to do this in a GUI. Even Windows Users seem to be effected by this bug and have to unmute in the audio settings. But for me the GUI did not work.)
On Ubuntu 20.04 when the G933 is stuck on Mute I go into settings -> Audio. Under Input if I drag the volume all the way down and let go of the mouse, then bring it back up, it'll unmute the mic for me.
