It's pretty common for subadults to go off feed. A lot of my sub adults gave me issues this year. They would NOT take frozen thawed, absolutely refused week after week. They took live for me alright, but some would even refuse that every now and again.

I've heard that if you keep them in the same room as breedable snakes they smell the pheromones and can be tough feeders. I don't know if that's entirely true, but that's what I've heard.