Jhin's W Passive on Enemy Champions

Hello Riot, I simply wanna report on a bug that I have noticed on Jhin or maybe it isn't I dont know you guys at headquarters can determine that. This has happened in several games. It doesn't happen during the first 5 minutes of the game but right around 10-20 minutes. Basically when you hit an enemy or if your teammates hit an enemy you get Jhin's W passive on the enemy champ of course. The thing is, I noticed that sometimes when an enemy champion gets rooted once the mark stays on them for the rest of the game. So when I land my W on them they dont get rooted despite the fact the icon is there. I tryed to explain it the best I could, Im not very good at explaining anything so I hope someone can understand what Im saying. If not let me know and I'll try to explain more better.