Lux Passive Bug

I'm not sure if this is a bug or not, but recently when I've been playing Lux I would go to auto attack a minion or a champion to proc her passive mark, the auto attack would go through but the mark wouldn't proc the magic damage off the auto. Like you would see the auto attack give normal auto attack damage but it wouldn't proc the mark or give the bonus magic damage its supposed to do. This doesn't happen all the time but it has occurred 5 or 6 times in some of my Lux games.

Is anyone else noticing this?