Game Mechanics: Upper Guk - assisting auto attack - multiple mobs

[Lammy]

So far this has only happened for me in upper guk.

Other group members have verified it is happening to them too.

When someone pulls 2 mobs and I use /assist and then auto attack:
-My character does not attack. (no animation or damage)
-My character does no melee damage.
-The mobs HP does not reflect the HP% decrease as group members attack it.

To fix it, I have to hit "ESC" and re-target the mob.