Thank you for the feedback, this issue will be investigated!
In order to help us, please provide the following information (please PM me the answer, or send it to Customer Support in-game):
UID* (Do NEVER post publicly your UID number on the Forum)
What device was used when it happened?
Is it related to a specific event (or another specific battle)? Or even another part of the game (when you purchase something, editing deck, entering in any of the screens, when you level up your Planeswalker, etc)?
If it is in a battle, a list of all cards in the deck and possible interactions that might have happened.
In this case, the more information the player gives to us, the better.