I'm not sure it's limited to mobs. I've been doing some quests on various characters this week, and noticed numerous times that when they speak to me they're not even facing me. Perhaps the mobs have the same problem, except that in the mobs' case, they don't aggro because they're facing the wrong way and so don't see any enemy.

Necrotech_Master wrote: »

npc aggro in trash mobs seems to have been messed up for quite awhile, there are even cases in some trials where some trash mobs dont aggro and we wonder why we are still in combat (kynes aegis is an example)

as far as i know there is also a general "aggro cap" as to how much initially aggros, such as when you are in FG1 and going to the 2nd goblin boss in the large room and theres like 3 mobs of enemies in there, but you generally dont aggro all of them at once unless you explicitly attack them

the problem your referring to is definitely not new though, its been there for almost a year, maybe a bit longer

Iv been doing my Undaunted pledges daily for almost 2 years now. Something has definitely changed. It's relatively sporadic, but it happens often enough to notice.

Here are some examples:

On Vaults of Madness, right before Iskra the Omen, when you're running up the stairs, there's a pack of mobs that run down at the group. After killing that pack, I noticed that 1 mob didnt run down the stairs and was instead standing against the wall not getting aggro.

On Wayrest 2, right after Garron the Returned, in that big area with like 20 mobs. There seems to consistently be 1 mob in the far right corner that doesn't get aggro. They just stand there while every other mob in the room is killed. If no one touches them, they just stand in the corner doing nothing.

On Direfrost Keep, right after Guardian of the Flame, it seems common to sprint to the platform room above Drodda's Dreadlord and pull all the mobs there. Recently, I noticed one of the archers isn't getting aggro and has to be killed on the way back. They're just standing there, not attacking or doing anything.

I wont make an exhaustive list here, but there are tons of examples that I'v noticed and I swear they didn't act this way until recently (u40?). There are also examples of range mobs pathing differently; running away while firing bows, only to stand against the wall and not attack anyone. They seem to hold aggro, but they don't chase when the group moves away, they just stand there fixed in place holding aggro. That isn't too new, but it seems to be happening way more recently.

I kinda feel like I'm going crazy lol. I need to take some ingame vids to show what I mean. Add on the myriad of new boss bugs that were recently introduced (like The Troll King in Blessed Crucible that I noticed the other day), and the awkward Skill queue behavior (taunt misfiring), and I definitely felt a down tick in game quality after u40. It's subtle, but noticeable to me. Like a chef changing ingredient brands; only the regulars seem to notice the change.