Flameblast Dragon sometimes won’t allow the opponent’s Planeswalker to be a target. Here’s an example…the first card in my hand was a full Kami War so I should have been able to deal 16 damage and kill greg.
Hello @TheHunter ,
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.