Master Yi - Highlander and Jhin - Captive Audience interaction/bug

First I am not sure is this right spot where to write it.

Problem is that when Yi is under his ultimate Highlander (Master Yi moves with unparalleled agility, temporarily increasing his Movement and Attack Speeds as well as making him IMMUNE to all slowing effects. While active, Champion kills or assists extends Highlander's duration. Passively reduces cooldown for his other abilities on a kill or assist.) but, Jhins Captive Audience (Jhin places an invisible lotus trap that blooms when walked over. It SLOWS nearby enemies before dealing damage with an explosion of serrated petals.) can slow Yi under the ultimate and that should't be possible. I am going to try it again in custom game soon and I will try to make screenshot of it or a short video.