I was hired for a position but after meeting my mentor and supervisor, they are not willing to train me.

I was hired for an entry level position at a big tech company in NJ. The mentor they assigned me isn't very fond of me. What's worse is he is the only employee that does our particular job, so getting any info from him was going to be tough. I have reported to HR once already that I am not taking place in what I was hired to do. They had a talk with my boss and supposedly said he would take care of the situation. 2 months later, my mentor gives me irrelevant tasks that really aren't contributing to my ability to gain knowledge. My worry is that I end up getting fired, but was unfairly afforded the opportunity to show my abilities to contribute to the company just because one person despises me. The only thing HR said to me during our meeting regarding my mentor's treatment of me was that maybe he now feels he is indispensable because he won't be the ONLY one anymore that can do our job.