Game will switch to Desktop only in Fullscreen mode, Windowed doesn't seems to be affected. I also turned all background processes off and let just the important ones (Steam, Arma 3 and nVidia driver app). Problem is still actual though.

My bad, slavic symbols actually work in ingame triggers, WPs and other ingame stuff, however they don't work in external sqf scripts and ext/cpp files using ANSI table, text documents with UTF-8 tables are ok.

@Killzone_Kid
Check the name of animation I mentioned - "acts_CrouchingFiringLeftRifle01" It's a cinematic shooting animation.

Just tried silenced Scorpion EVO 3 (SMG), which makes just tick-tick sounds, same as MP5SD6 and there is the same problem. You shot one guy and 50m away guys will just turn around and shot you.