NPC not attacking the player (Metro Exodus)

Enemies (NPC) stopped to attack the player, on the Volga. And with the start of the game until the passage of some places of this Chapter it was fine. When close, shoot in front of them or in them, throw a grenade to kill one before the other - also no reaction.With mutants there is no problem.
The most interesting thing is that I do not understand at what point they ceased to attack, because I always killed them in stealth and thought that remain undetected ). Anyone had anything similar and how to fix it?