Game Mechanics: Gnolls in HPH *never* interrupt casts

[Malrubius]

I don't know if it was this way in classic, but the mobs in Highpass Hold never interrupt my casts.

I can be meleeing multiple mobs, and cast even a spell with a very long cast time, and the spell always completes.

I also never see the "regain your concentration" message.

All these mobs are green to dark blue to me, and I've been grinding faction here for 100s of kills. Not a single interrupt looks suspiciously like a bug.

EDIT: Okay, casting can be interrupted, but with Stuns only (as in the 2-3 second variety).