[Gameplay] Vi not dying after reaching 0 hp

Happened to me yesterday. Vi gets crit by cait and reaches 0 hp. She can still autoattack and get back health. Whats bothering me is that her lifebar isnt visible for a short period of time, making it impossible to attack her again before she can get off her aa.

If there is any explaination for this or this isnt a bug please tell me.

Matchlink is in youtube video description for additional info about build etc.

Disclaimer: This video is not about my shitty cait mechanics :^)