Varus Q channel interrupted; broken cast for remainder of game unless you reconnect

I was in the middle of a ranked game as ADC Varus, and in the midst of a 4 person gank, I was casting Piercing Arrow, but was stunned by Amumu and knocked up by Janna and died instantly. After respawning and coming into lane to defend turret, it wouldn't cast. It was meant to be shot at the minions and the laners pushing, and I can hear the "click" noise you hear when abilities are cast, but it refused to channel. I decided to reconnect and 2 minutes later it seemed the game was in the enemy team's favor. I literally lost a ranked game (demoted to B5 in the process) all because of this. I asked if it was normal in all-chat but no one seemed to care. I'm sure it's channels in general that have this bug because I've played other champions with abilities that won't cast at random from certain circumstances but it wasn't in a game as serious as ranked. I hope this gets noticed and I'd hate to be discouraged from playing certain champs with bugs that cost you the game.