NOT related to behaviour of AI
Reproduction: yes / ocassionally
Reproduction steps: unclear

Behaviour:
Mobs dont face the player direction to shoot. Audio of shots being fired not heard. Impact on player char not shown in visual or audio feedback. HLT bar update not at all, very slow or normal.
Sometimes even no animation / movement of the mob/AI can be seen, not even any sound is heard if mobs are shooting the player.
Can happen with single mob or mobs in groups.
More likely happening if mobs have already aggro on player, or HAD sometimes aggro (lost it).

As there is no impact noticeable from weapons hitting the player (only if HLT bar is watched and correctly updated) the player is likely to die without noticing whats happening at all. Critical for low HLT classes.

( Map sectors in the wastes seem to have higher update priority than for example dungeons in DoY ?? )