Game Mechanics: Undead flee @ Low HP.

[Versus]

I searched the bug section for a similar thread and didn't find anything, which I was surprised about.

I was under the impression (or maybe I'm just dumb) that undead was not supposed to flee @ low hp. This mechanic is acting different in different zones.

-Undead mobs in Karnor's Castle for example do not flee with low HP.
-Undead mobs in Kaesora run @ 15 or 20%

Again, I don't know if this is a blanket mechanic or changes varying on level or zone, just figured I would bring it up.