[Gameplay] Vel'koz's ultimate interrupted...for the rest of the game.

I was playing Vel'Koz and I went to use my ultimate and was killed by Garen's Q right as I was casting it. When I respawned, I could not use the ultimate anymore. It was highlighted like it was ready, but when I would push "r" nothing would happen, no ultimate and no cooldown counter started. Just nothing, it stayed highlighted. I thought my keyboard was having an error so I tried to use my mouse to activate it, but still nothing.