Blizzard Brawl allowed me to target a creature, then the “give +2/+0 and prevent damage” part worked, as there were over 9 snow gems on board. Then, the Fight mechanic did not happen afterward.
I am not sure why the Fight part triggered fine in other matches- unfortunately, I cannot remember if the fight part worked when there were less than 9 snow gems on board.
Lost my perfect score in Doomskar Claimants due to this bug- I have submitted a ticket for compensation.