Yep, this is the same bug as
this thread. These bugged mobs don't attack you if you shoot them from far enough away (out of their aggro range) and you can kill them without ever being attacked if you can keep at it. But if you get in their aggro range they will attack you for the usual 22 hits, then leave you alone, then come back for another 22 if you stick around long enough. For some reason the game doesn't fully recognize that you're doing damage to the mob even though it shows the damage you do and the mob's HP drains down.
It seems to happen a lot with rudoeds and deminers between NU and Turukhansk but I don't think I've seen it happen with any other mobs. I don't think it's the area because the Antelopes in the area all act normally.