Thresh pull not stunning/pulling towards on hit

I landed multiple pulls and my chain just linked with the champ and ran away with them.... it's hard to describe. Basically instead of rooting the champ and pulling them towards me I could see the chain attached to the champ and they would continue to run whatever direction they wanted. Tristana saw it in the game I was playing too. Sometimes it would work as it was supposed to but against rengar, mal, and garen it didn't work a single time. It's either a glitch or a multiple hack but it looks like dark star thresh is disabled due to a bug and I think thresh in general has a bug.

Thank you.