Jhin W Mark wont go away

Just lost a ranked game cause these marks from Jhins passive were appearing on different enemy champions when i wasnt even close to them. They werent damaged or anything so in teamfights i would assume they were marked and go for the snare but it never snared them.. i ended up losing over it cause i kept going for engages on marked targets for a snare but it never snared them.. Rip lp