Vi Q not working late game?

So, I was playing a normal match on summoner's rift as Vi with my friend, and late in the game, my q wouldn't work. This is not an issue with my computer as I could type q in the chat just fine, but I could not preform my q. It was working the next game, which is weird. It may just be a small error, but it was really frustrating. Thank you for reading!