Game Not Valid Message
Anyone else getting this message in an Arena battle and any idea why?

Its happened 4 times now in about 50 games total and the situation is the same in each case. Disposed of the opposition and are in the process of attacking the tree thing at the end, plenty of time to go when the game appears to end early and displays this message. It also goes down as a loss. I've never seen it before in general play.

As this feature is only recently out of beta testing it might just be glitch they haven't fixed yet which is OK but recording it as a loss isn't right, I'm quite capable of losing without additional help.