QSS stops chains but snares you

I was playing a normals with a karma on my team and a LeBlanc on the other and both me and the enemy Kalista has Qss and we both used it to get rid of the chain (me getting rid of leblanc's and her getting rid of Karma's and it stopped the chain but snared us immediatly. I have never had this happened before but it cost us the game because of it. I wanted to get it known so it doesn't happen to anyone else.