Fiora, Gameplay Bug, multiple "vitals" on enemy champions

There was a bug last night while I was fighting a Quinn in the top lane.

A. I don't know how the bug was triggered but while trading with Quinn, Quinn would gather more than one "vital" spot and it would cause Fiora to lunge (her q ability) to the improper vital sometimes. Note: hitting the 2nd vital wouldn't trigger her passive either. So I would have a 50/50 chance to hit the right one.

B. I would cast Fiora ultimate ability (Grand challenge) on an enemy who would die within a second after the cast and the ability would not trigger the minimum, causing me to also loose the ability (put it on cooldown).

I think Part A was triggered by Quinn using her bounce ability at the same time I would lunge. But I am not certain. And Part B, I don't know if this of intended or unintended, thanks for reading, I don't have anything more to offer (screenshots/gameplay).