[GAMEPLAY] Lux "e" bug

I was playing a co-op vs. ai game not too long ago before making this post. I was playing as and about 5 minutes into the game, I was unable to use her "e" skill. This went on throughout the entire game. I thought dying or leveling the skill would make the skill usable but unfortunately this went on throughout the entire game. I took a screen shot around the 14 minute mark of what I was seeing when I hovered over the skill.

Update: Forgot to include how to reproduce to bug. I'm unsure as to how the bug occurred. I was able to use her "e" 5 minutes into the game, but there was a time when I casted it and the ball of light that would usually land on the cast area didn't appear. At that point on, I was unable to cast her "e".