[Gameplay Bug] Xerath q Disabled if Knocked Up During Channel

Ok, so Xerath is one of my favorite champions, and I've been playing him quite a bit recently. A month or so ago, I was playing a custom with my friend, he was playing blitzcrank. We were dueling, I got knocked up, and then for some reason, I couldn't use my Q ability (arcanopulse) at all for the rest of the game. The same thing happened to me in actual games both ARAM and summoner's rift. In other words, if you get knocked up while you are channeling your Q, it gets permanently disabled and you can't use it. The only way I've found to fix the bug is to exit the game and reload it, at which point I could use my Q again. This seems like a pretty major issue with Xerath to me as far as gameplay goes.