After upgrading to Kubuntu 21.04 (Plasma 5.21.4), I can no longer adjust audio volume with the volume keys on my keyboard. I'm not sure if it's related, but I also noted that the "step" option is gone. I prefer a bit finer control, and usually use 2% instead of 5%.

I'm fairly certain the keys themselves work in KDE, as I tried to rebind them in the 'shortcuts' part of the system settings, and that went fine. It just complained that it was already bound to the key I pressed (volume up). But when I press they keys on the desktop, nothing appears to happen.

Kubuntu 21.04
Plasma: 5.21.4
Frameworks: 5.80.0
QT: 5.15
Kernel 5.11.0-16-generic x64