Jhin mark permanently on, but not being able to root someone

I was playing a game when some time through Ryze ran at me faster than a Sion ult and I W'd him as Jhin because he had the mark on him, but when it hit it didn't snare him. When I said something about it all he did was try to cover up the obvious crutch he had on me, but the next time I saw him, he still had the mark. So I tried to snare him, and again it did nothing. Riot please fix this it's impossible to know when to snare people with this on.