[Gamplay] Lux E bugged - cannot cast

Happened during a ranked game about 30 mins in. After casting my E during the game - but I wasn't recording at the time as I didn't expect it to glitch like this - and it randomly disabled the skill and I couldn't cast it again for the rest of the game. Haven't had time to test it out to see whether its recurring but this has happened to me once a few patches ago.