Ezreal bug with Deathfire Touch

Currently deathfire touch is bugged with ezreal's q. It doesn't deal the DOT from the keystone when they are hit with ezreal's q. To test just pick ezreal and any other champ with ezreal having deathfire touch. The mastery says that abilities apply the damage so ezreal's q should as well. I imagine it doesn't because it is coded as a sort of auto attack. However, this mastery goes from great to useless on him if it doesn't prock on his q and based on the mastery's description it should proc on his q.