I've got an issue with Pepper Gun.

I've noticed that the sound made by the gun (when the pepper is being sprayed) has disappeared.

I'm not that far into the game. First visit in UNATCO, just after the statue mission.

I've started a new game and the pepper gun sound is there.

I'd like to fix it on my current save.

I did a quick test and it seems to happen when I transition from Liberty Island map to UNATCO HQ map on the first mission.

I'm using GOG GOTY version with New Vision and HDTP.

Did anybody have similar issue?

It's a common problem together with sound/music stuttering, sound/music gone, etc.... (under Win 8.1+ if i remember right).

If you#re using Win 10, this should help you to make a stable setup

https://steamcommunity.com/app/6910/discussions/0/613936673444809191/

aside from this, there's a number of post that solve minor problems, some here at gog.

If you know the story you can try this
https://www.dx-revision.com/

and nexus has quite a number of mods and fan-patches that (try) to solve every problem out there.