Sion W Health gain passive bugged

I played a Sion game about an hour ago and the whole game my W wouldn't hold the health stacks like it should. It constantly read that the bonus health provided was 0. I also watched to see if just the number was bugged, but I killed a few minions and my health didn't increase. I was also playing against another Sion but he said he wasn't having that problem. Just wondering if Riot is aware and looking in to this.