Experiencing the same glitch. Just started a duels run using the following code with priest: AAEBAa0GD+UE1wryDKGsAtHBAtjBAqfLA8vNA9fOA+PRA+LeA8rhA/jjA4SfBIWfBAAA
The deck created successfully, but I am unable to retire, and attempting to start a new game results in “There was an error starting your game, please wait a few minutes and try again.”
Another post (There was an error starting your game. Duels Error) suggests the import may have contained a card that is not legal in the current Duels format.