SUMMARY

I have a Corsair K70 keyboard with extra media keys (play, pause etc, mute and volume scroll).
Play/pause etc still work (Quod Libet interprets them like it used to) but mute and volume scroll don't work at all.

The strange part is if I add an Audio Volume widget to my desktop, mute and volume scroll work like they used to, but only as long as that widget is on my desktop.
If I remove it again, mute and volume scroll will go back to doing nothing.


STEPS TO REPRODUCE
1. Use a mute media key or volume scroll media key
2. 
3. 

OBSERVED RESULT
Nothing happens (unless I add an Audio Volume widget to my desktop)

EXPECTED RESULT
All sound should (un)mute when I press the mute button and volume should go up/down when I scroll the volume scroll

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 5.26.0
KDE Frameworks Version: 5.99.0
Qt Version: 5.15.6

ADDITIONAL INFORMATION
There's also the issue that when I plug in a microphone, the Audio Input list of the Audio Volume applet will begin shaking violently, as if it's continuously picking up the new device and dropping it at a high rate.
I should probably file this one separately but have no idea how to troubleshoot it.