Lux's E skill locks and can no longer be cast for the remainder of the game

Lux's E doesn't work anymore when mousing over it it's simply a little grayed out and says the skill cannot be cast at this time. At the time I had a i believe and maybe a or . I tried restarting and resuming the match and dying but the skill remained locked and unusable the remainder of the game. It might have something to do with the new addition of it being able to be recast in the air to detonate upon arrival because I have never had this happen to me before.

Happened this match http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/1867753780/220705289