Azir's Ult only works half of the time

So I just played a game as azir after patch 4.19 came out and during the game whenever I used my ult about 50 - 60 % of the time my ult would go right through the enemy champion - not to any damage and not push them back - and then it would let enemy champs walk through it with no qaulms - as I was PvP fighting i didnt take any screenshots but it was definetly a real issue and it should be looked at.