Anytime you roll a D20 it is supposed to shuffle the board. This does not work with Mordenkainen’s ability.
Also, not a planeswalker-ability issue since it works correctly with Zavriel
Hello @QuiksilverHg , Thank you for all the information provided, this issue will be investigated! If you have any additional information that you consider relevant, please don't hesitate to send me 😊 Rebeca.