A brief google search lead me here and I cannot find an official bug report site (please provide me one if you know it) so I'll be compiling the bugs I've found in the multiplayer for various classes here.
When a ranged class attacks the pots/vases that contain gold, occasionally they will sit and respawn but they won't allow you to retarget them (ranged class)
Only melee classes can destroy them after they respawn.
Spirit Bomb (May have the name wrong, but its the bottom right ability on the necro tree)
Once the spirit of the enemy has been controlled, most of the time they just sit where they are unless there is an enemy directly next to them.
Suggested Fix - Have them attack what the Necromancer is attacking.
Demon Commander Difficulty (This is feedback, not a bug)
With various parties, I've been able to clear most of the scenarios but the Demon commander is one of the most frustrating experiences I have had in the multiplayer. it's not challenging, it's abusive. The rate at which he jumps into the ground and the lack of time to react between his 3xScream disorient attack will almost one shot anyone - even tanks.
I'll post more as I find them.