Tristana ult bug vs Lee Sin Q [BUG]

I was in a game playing as tristana, pushing the turret when lee came to gank me. Lee hit me with his q and followed up on it. When I tried to ult him during his he took the damage of my ult however there was no knockback from it. This happened twice in the same game only one of which i have the footage. The second time lost us the game since I would have knocked lee back. But it didn't work so I got insec'd into the enemy team.

This bug happens when you ult as tristana while the lee is flying towards you.

Hopefully this bug get's fixed soon since it was incredibly annoying to deal with and made me lose a game.