Hostile coworker

I have no idea what this person's problem is with me since they seem to get along with everyone else. A few months ago this coworker started being really hostile and unhelpful towards me, say when I call for cashier backup. Won't speak to me and if they do, they sound hateful, like me existing just infuriates them. I dread having to work with them as it causes me so much anxiety. I've spoken to the SL and other leads, but the issue continues, so I'm seriously considering contacting HR. TLDR: coworker loathes me and is unhelpful.