I know the adventuring public are gonna kill me for this BUT......
...in the Bowels sometimes the Earth Elementals don't attack or the move in 'slo-mo' meaning they attack, but at like 1/3-1/5 their normal attack rate (maybe one attack for every 4-5 of mine).
They also tend not to chase at all and tend to get stuck quite easily when taking a corner really close to the wall.
Additionally, the animatrons have the same problems, though to a slightly lesser degree. Their attack rate seems to be halved. Also, the Ranged Defenders take nearly 6 to 10 seconds for the animation on Magic Missile to fire off. What happens is the little ball of conjuring energy appears in front of them during the casting process, but it never fires off until like 6-10 seconds passes.
At first I thought it was just lag or something, but I've gone into the bowels alone when only 17 people have been on the server and the same thing happens.
All other creatures (zombies, beetles, etc) seem to be fine.