Renekton E Bug [Gameplay]

I recently played a game as Renekton and noticed that sometimes when I used the first cast of E and hit someone, the second cast wouldn't always be able to be used. The icon for Dice would appear as well as the flashing on the icon that signals that you have a limited time to use it, but it was unable to be used and the CD of the ability would start counting down. This happened a few times in the game. I think it mostly happened why I used the first cast of E at point blank of an enemy champion.