The weird bug still persist when the loaded game session results in every object on map being duplicated . This means two times the enemies, weapons, health, ammo, etc.
I start game. I save game. Then load game. All enemies which were woken up - disappear. All enemies which weren't - are getting duplicated. All items like ammo, weapons or health duplicates too. So where only one enemy should be standing - now there is two of them. But all duplicated objects still occupy the same single block, so you can't notice it until you pick items or woke enemies.
When I die and respawn - this doesn't happen though.
P.S. Also - projectiles sometime can't hit player if he's crouching.