Sounds like a raid thing. Has been happening for some champs in regular AQ.
It's just a bug... you are getting attack bonus too. So just ignore it. It's not breaking anything. It's AQ, Nobody cares what happens in AQ. Next week is coliseum, then raids, then coliseum again.
Good point about the Raid thing. It's the RAID clean moves boost! There is no boost though, so not an exploit. The only advantage is the cleanse, I guess.