This is still broken but a friend and I have a work around.
Click on the crossed swords icon for direct challenge and select historic brawl for your format. Have your opponent do the same.
Select the deck you want to play.
Click away from the challenge and open the friends chat. Challenge them from there BUT make sure you change the format to historic brawl. The deck you chose previously should be auto-selected. Click challenge. Friend accepts and you should get a loading screen with your names and avatars but your deck box will be the missing image placeholder art.
NockAndLoose#20705
This is still broken but a friend and I have a work around.
Click on the crossed swords icon for direct challenge and select historic brawl for your format. Have your opponent do the same.
Select the deck you want to play.
Click away from the challenge and open the friends chat. Challenge them from there BUT make sure you change the format to historic brawl. The deck you chose previously should be auto-selected. Click challenge. Friend accepts and you should get a loading screen with your names and avatars but your deck box will be the missing image placeholder art.
Hope this helps until wotc figures it out.