Katarina ultimate bug

Katarina's ultimate is currently bugged in that her q would not cancel it. Discovered the bug in an aram, was able to replicate said bug in a custom game. Walking, w, and e were able to cancel the ultimate as normal. Kind of hope you guys can get down to the bottom of this, it made playing Katarina extremely frustrating and confusing.

Edit:

1. This is a Gameplay bug (sorry, I realized I had to put it in the title after I had already posted, my mistake)
2. See Above
3. Simply use ultimate on an enemy and then try to q during the duration. Q should normally cancel the ultimate, but instead does not, and goes off after the ultimate duration.
4. I've managed to reproduce the bug every time I have played Katarina