about 10 minutes ago i used whirlwind enemies on the temple map with hell mantis all other mobs moved except him and since he didn't reload like they did i imagine he didn't random the same squares but i could be wrong.
Is it a large enemy(4 squares)? I had the same thing with one of those, perhaps they're too big to be whirlwinded.
he is 2x2 yes but i know i have done it to the 2x2 goblins at least so its inconsistent if its not a bug