In the first mission of the Wild Plains quest (I believe it’s called Angry Spirit), you fight only the Angry Spirit (Sunweaver). When using a troop that hits multiple targets (like the Dust Devil ), the Sunweaver is taking all four hits instead of just one. It’s like the game thinks there are four opponents instead of just one so it puts all four attacks on the one opponent.
Unfortunately I don’t have a second account to record what happened (and obviously we can’t replay quest missions) however I did notice this happen twice in the same battle. If this just affects this one quest mission, it’s a pretty minor bug but I wanted to report it on the off chance it may be affecting other gameplay situations.