Most often when you fire on an NPC with a ranged weapon or a hack attack they will engage in combat. However, sometimes they will simply ignore you and continue to wander around while you blast away at them until you finally kill them off. This can happen multiple times in a row and rather than simply shoot these fish-in-a-barrel, I often feel obliged to interlock with them just to get their attention. This happens independently of how far away you are, as hostile NPCs can simply ignore you even though you're right next to them, and is also independent of the their relative level as it happens wtih blues, yellows, or oranges.
NPCs ignoring ranged and hack attacks
3 posts · 2007-05-21 19:57:36 to 2007-05-22 05:36:22
Yeah, sometimes they get 'trapped' in doorways and dont react when you attack them, this is how 3 of us killed the level 70 sim in the org construct 
I dont know how that happens.
Also, then NPCs leave the mission area, they dont react to damage as you aren't on the mission area and dont have anyone to target, this is the same reason you can heal in the Elevator while they stant just on the other side of the elevator and dont attack you.
I have been experiencing this frequently too. Not just in missions, but while farming as well.
MrMatador