Looks like a policy change is being enforced, I'm closing this bug to save gdrewb-valve a little effort. | This bug was closed because the issue concerns the game and not the Steam client. Please contact the game developer on their official website with this information.
Nothing extracted yet.
When the trader closes at the end of any wave, the Killing Floor client stalls for a moment and ignores any keyboard (or all input) events during that moment, so if you release a key during the stall, then it becomes a sticky key until you mash it again. It seems kind of frivolous to report this, but a lost clip of ammo has the potential to enrage some players.