I encountered what I believe to be a bug.
I was in the Light Side Combat Mission at Rear Flank territory, and was fighting with my General Skywalker + 501st clones.
On the last wave there was an 8 stack B2 droid. And contrary to what happens, eventough multiple units hit it in the same attack, the stacks only decreased by 1, it meant I had to take 8 turns before I could kill the unit.
I don't believe this is normal, and of course it cost me the ability to complete the wave.