We had the same issue with our new PB and adding a smaller hide worked great. Many people gave me some great advice but this was the key. He is about 6 months and we moved him into a 20 long and I think everyone is correct the cage size was a little much for him. Added a much smaller hide on warm side and he loved it next feed cycle he ate 2 hoppers like they were nothing great feed response with zmbie dance. Being a little new to Pythons I was very thanksful for the help. When I contacted the breeder he was kept in a drawer rack system and moved to the pet store and kept in a very small container so smaller hide worked wonders.
Robbie