[Gameplay] Unable to basic Attack as Kayle

So in two separate games in the past two days I have encountered what may be a game breaking bug. Both times I was playing Kayle, facing off against a Fiora first then Yi second, both times the enemy champion was in full vision, I was Lvl 6 or greater but less than 11, and in the middle of a fight I could no longer basic attack.

Yes I was in range, yes the enemy was visible, yes I clicked on them -- many times, my 'E' did nothing, lasted for 1-3 seconds, just long enough to get killed for standing in place like a dumb ass.

This issue breaks the game and makes Kayle even more difficult to play early than she normally is.