Glimpse of the void on Hecarim was stuck on 98 %!!

I was in a game playing and while i was in game i used and then used and was rushing down bot lane to use my ult on 2 people , i used it and backed off to bring the minion wave to siege the tower so i auto attacked the minions but my glimpse of the void wouldn't proc so i looked at it and it was stuck on 98 and wouldn't charge any further.