There's a random bug with the AK-12's gunshot sound where the person being shot at can't hear the shot or the bullet crack, just the noise of impact, at very close distances (<100m) as well.
It usually seems to happen when AI is firing on a dedicated server. Maybe a locality issue?
Unable to repro under test conditions so far. However, randomly occurs on dedicated servers when AI are using the AK12.
Possibly affects other AKs too, unsure.
It's frustrating because whole fire teams get wiped out without being able to figure out where they're being fired upon from.