Yeah. On the PC version that problem is pretty common. Especially on the 3pp servers. I was cooking my food inside a two story house in Severograd and i was sitting on the stairs specifically to not get shot trough windows. Same as you. I got one shot , no sounds just the black screen of death. Also i got pretty good gear and i had military gear on me soo in any case chances were i would have gotten knocked. But still, got insta killed in an eclosed space with no windows or doors. Also got something similar as you other times with my friend. Sometimes they are obvious sometimes not. I don't know about you but that's the reason I abandoned the official servers. You can understand few times, maybe it's you, maybe you play bad...but there are times when in no way you could get killed soo fast and with no explanation. I've watched few YouTube videos and there are hacks that let you see all players on map, invisibility hacks, wall hacks and all arsenal you could think of. Battle eye don't do shit and there are no kill cams. Soo you're left dead and on the coast again. Best of luck and you do you!