Game Mechanics: Mobs Fleeing in Water

[mefdinkins]

So, I've had the worst problems with mobs fleeing in water.

In Lake Rather we had 10 people chasing the necro epic guy as he seemingly teleports in/out of water and no one can hit. In CS, Oasis, when mobs flee into water they are near impossible to kill. I've had to evac, I've had to FD and let all mobs reset, and I've died trying to get that last 3%.

Is this a bug, is it just me!?