Played 3 matches, occurred in all of them. Every single time I was CC'd I could still slightly move my character around. It looked like I was being dragged by Skarner when I'd right click to move and I'd move just a tiny bit at a time.
Not sure what's going on but, it's pretty busted. I survived so many things that I shouldn't have because of this bug. lol
Literally walked right through a Gragas ult without it even affecting me, moved towards an Ashe even after she ulted me.. forcing her to Flash, and lots of other ridiculous movement while CC'd that definitely should not be happening.