General: Mobs detecting me while in stealth act weird
Sometimes when mobs detect me while sneaking around, they will aggro and look at me, but they won't attack at all. What also happens sometimes is that a mob will aggro and run towards me, but he will run so slowly that I'm able to outrun it even while my movement speed is reduced, after which the mob will just run back and still leave combat, and I will still be in stealth, even though I was "officially" in combat.
What's always a 100% occurrence is that while in combat I will only be forced out of stealth by suffering damage, not by actually being detected, though I'm unsure whether this is intended or not.