Lux's e disappears, can't cast the rest of the game

I my most recent match (Ranked 3s as Lux ) I got a strange error where I cast my Lucient Singularity (e), it never made it to the ground. After that, my e never stopped being greyed out, and I couldn't cast it the entire rest of the match. Every time I do, it gives me the "you cannot cast this right now" error. Even when I quit the match and rejoined, the problem persisted.

I don't know how I managed to do this, or if I could make it happen again.