Lux Bug: E randomly disappears and is disabled

I just finished a lux game today and became incredibly frustrated 14 minutes in. After I used by e, the projectile fired, and then disappeared. i was unable to use the e for the rest of that game, and I even restarted the game twice. I am not sure how this bug is caused specifically, but I believe it is the game not being able to find that the e timed out, so the skill became disabled.