Possible Shen/DMP interaction bug

Was just playing Shen on an ARAM and rushed Dead Man's Plate. I don't have a screenshot to back this up, but I noticed something weird. At 100 stacks on DMP, if I landed a taunt on someone the animation for the DMP discharge would go off and they wouldn't be taunted. This happened 3 or 4 times (that I noticed) over the course of the game.