Lux E stopped working in game

In a game my Lux E (Lucent Singularity) bugged and became unusable. At about the 18 minute mark I threw it at some minions right on the edge of the fog of war, then lost vision so the E went into the fog of war. I was spamming the key to make it detonate so when it never appeared I figured that had happened. But when the minions came back into view they were not damaged and my E was not castable. The spell bar showed the icon as it looks when E has been cast and is waiting for detonation. Dying did not fix this, nor did reconnecting. My E was completely disabled for the rest of the game (my team had many suggestions, but none of them worked either). I've heard of similar issues where leveling the ability fixes it, but I had already maxed E when this happened.