[Gameplay] Lux In game BUG PLZ FIXXXXXX

During my mid of Rank game, I was using my E skill to clear the waves. And out of sudden, the skill board indicates that E skill is disable, and "YOU cannot cast that right now"

The E skill (lucent sigularity) turned grey, and could not turned back even died and revived!!! Cannot use E even changing items.

No loss prevention after the rank.