Lux E Bug

I have not experienced this personally but am writing in the stead of a few friends. When my friends play Lux, they occasionally cannot use their E at all in their games. They tried to restart their clients and pcs. It sometimes works for halfway into the game and then disables itself. Other times it can happen from the beginning of the game. The text says "This spell is not ready yet." as if it is on Cooldown but the Cooldown has already ended. As I've said this isn't just happening to one player. My affected friends live in two different sections of the Oceania region also, so I doubt it is area based. Thanks for your time. I hope this is solved soon.