Alistar WQ combo occasionally not working for an entire game

I Play a lot of Alistar and I am good at landing his WQ combo I might miss the combo 3 or 4 times during the entire game. Occasionally the combo will bug and I won't be able to hit a single combo the entire game. I am not playing on bad ping or doing anything differently from when I normally play the champion the combo just does not work. I try to mess with the timing of pressing the buttons and the end result is the same the combo will not land the enemy I target with Headbutt and charge towards them and click Q with the proper timing and the enemy flies away from me without getting knocked up even though I hit the ground upon arriving at the enemies former location. this makes Alistar virtually unplayable because he has no way to initiate fights or catch targets without being right on top of them or sending them flying away from his team. I would greatly appreciate if you could fix this bug so I can play my favorite support without worrying that I am going to be useless during the game.