[GAMEPLAY] Vi - Knock-up Bug when Using Ultimate Causes Her to Float in Place

I noticed a bug on Vi the other day where I ulted a Nasus to dodge the knock-up from the ultimate of the enemy team's Fizz as I started my cast. Now, Vi is supposed to be unstoppable when casting her ultimate, meaning she cannot be knocked up by the likes of a Fizz ultimate during the cast. However, this particular interaction caused my character to float in mid-air (uncontrollable) and to no longer fly towards my target.

As I floated, the enemy team surrounded me and Nasus casually walked away without ever being touched by my ultimate. The enemy team proceeded to annihilate me as if I was suffering from a lengthy stun and we lost the game. Similar things have happened with other knockups/pushbacks as I cast Vi's ult, but to a lesser extent where it merely slows down the travel time or displaces the position in which I land relative to my target (as depicted in the first picture).

I find this bug defeats the purpose of timing Vi's ultimate to evade crowd control, as it de-incentivizes doing so because if it is mistimed it can do much more harm than good. Below is a screen shot of the interaction from the replay of the game I described.

To reproduce this bug:

1. As Vi, stand near Fizz's shark on the ground (not sure if the bug produces if the shark is directly on Vi, as I was only standing near it)
2. Cast Vi's ult on a target in range exactly as the fish is about to jump, which would precipitate the knock-up
3. Notice that Vi will float nearly in place, moving ever so slightly toward her target, instead of ignoring the knock-up and finishing the animation.

I have created a word document with screenshots from the game where this occurred, though am unsure of how to attach it to this post. In these pictures you can see the Nasus walk further and further away as Vi "stands" in place, unable to control. If you know of a way for me to either post these pictures here or email them to someone who would like to take a closer look, please let me know how I can do that.

Thank you for reviewing this situation.