Vi's Q Ability Suddenly Stops Working?

Well, it was a typical match as me playing Vi jungle, and everything was going pretty smoothly until I noticed about mid game my Q ability suddenly stopped funtioning. I pressed my Q key repeatedly and making sure I wasn't going crazy because I kept looking and squinting to see if it was on CD. I clicked it many times also to see if that worked but alas no luck. I could hear the toggle sound it makes though, oddly enough. No, my Q key works just fine as you can see here - QQQqqQQqqQQqqq. Heh. Anyway, I know it's a minuscule bug, but I just wanted to address it. Q - Vault Breaker