I'm having the same issue, only ambience and vehicle sound are playing. Everything else is silent - the weapons, footsteps, UI, etc... Haven't installed anything new either except updating the core mods so I have zero idea what's causing it since everything is working fine before. EDIT: I found the culprit for my issue, it's the "NCPD siren volume up" mod, literally one mod. So check for any mods that mess with sound and remove them, it might help.