In Arena with Shaman I played Evolve on 5 minions, and after the opponent’s turn when he killed my Unstable Ghoul, I could not attack with my Defias Ringleader. On the match history its clearly seen that I DID NOT attack with it, I only played 1 6-drop with taunt and used my hero power.
On my next several turns the bug continued, and it did actually cost me the game, cause I was 2 off - right the damage of this bugged minion. Also I could not even point my coursor on that minion, and it wasnt in sleep like minions on the right side, which I just played.
https://imgur.com/pENYS40
This sounds like a variation on the old “charge/rush” bug, where a minion can sometimes become unresponsive when clicked while the summon animation is still playing. Though much more rare, I have seen other reports of this same thing happening with Evolve. Do you recall if you clicked on or hovered over the Ringleader while the Evolve animation was still playing?
BTW, the original Charge/Rush bug has been reported as fixed as of the Rise of Shadows release, but it is possible the fix only addresses the issue while summoning and not while transforming. Or it is of course possible that this issue looks similar but is in fact not the same at all.
If a minion is found to be non-responsive like that, you can try to force-quit the game (Alt+F4 in Windows) and quickly restart it to reconnect to the game in progress, and thus reset your game client. That should unglitch the minion. Hopefully you do it fast enough that it is still your turn.
I don’t remember exactly, but I have a habit to play cards like Evolve with “throw away” motion, so I guess I couldn’t click on Ringleader while evolving.