It looks to be grabbing all keyboard input ‐ if you open the steam overlay, the adjustment works.
I don’t have this device, but rather tested by picking some temp. shortcut combos for volume up/down/mute.
my issue occurs only if the game is in Fullscreen mode only
Pro tip: Bringing up the in-game Steam overlay with shift+tab allows all those keys will work since it releases any input grabs the game has
Closing old non-Valve issue (can still be found in search).
Nothing extracted yet.
Note: using Logitech G15 (1st edition).
When using the volume wheel on my keyboard at the Linux desktop, the volume adjusts as normal. From within Killing Floor, I cannot adjust volume via the keyboard. This is a minor issue, as I have an in-line amp I can adjust, but it's still frustrating. This behaviour does not occur under Windows on the same machine.