[ GAMEPLAY ] As Ezreal sometimes my Q doesn't do the damage on the enemy champion

When I play as Ezreal sometimes when I Q a champion the damage does not affect them at all in anyway and this isn't the first time it happens to me ever since the new 7.9 patch, I don't know what's wrong and this also happened to many of my friends playing other champions such as Caitlyn's Q too, or Draven's Ult, etc

1- Simple you press an ability and the damage doesn't work... 2- You tilt because you die and the enemy didn't 3- You lose the game because that kill could have changed everything :)

https://www.youtube.com/watch?v=2QMPfAH6eYw&feature=youtu.be