I have the same issue, worked fine at start of alpha, then after a update it stopped working and has not since. Afterglow wireless headset.

Cannot hear my weapon firing.. can hear casings hitting ground and can hear impact of rounds.. Reload also is audible.

edit I finally managed to fix the issue. In my sound mixer where you choose what you use to playback sound. Instead of using the headset as the default device, I selected speaker instead. It is working fine now.