Well I didn't know you could have multiple targets on the field at the same time, all marked by the same JKR as I have never seen it before, so that may not be a bug
Not ever sure what the bug might be, just seemed odd behaviour on the marked front and then having a 5 toon mass assist do so little damage, the whole fight just felt off tbh
Sorry I cant be more specific. I did check the opponents stats.just in case he had a 200k protection Jolee or such but the stats were what you expect from a top 100 squad arena team