Kat Q bug?

I have played a lot of Katarina in the two years I've had league and this is something i've noticed happen quite a bit, so often in fact that it cant be contributed to lag or me comboing wrong. The problem happens in two instances, I throw a q as i die, i see the blade fly through the air but then I die and the q just cancels its in mid air and hits nothing. And the same thing happens when i throw it at a Kha'zix or tristana which are the two its happened with the most, I throw my q as they jump and they are low health, low enough that the q would kill them no doubt, and yet when they jump over a wall into fog of war, nothing happens. Its like it got canceled, i would type and ask them if they got hit with it and they say no, but i see the animation on my screen. could it just be me or is this a bug that happens to others as well?