They like very tight hides.
98 is too hot, 93-94 max. Ball pythons can feel very insecure in a glass tank so he maybe hiding where he feels more secure as opposed to the best temp area. They like to feel out of sight in a tight dark place.

Your enclosure is nice looking and the pastel is real pretty. That hide on left isnt too small but the door is to open, they want to hide out of site in the dark. With a bright light shining down on him and that large entry hole he maynot feel secure in there. I would loose the light, they dont need it and he will feel much more secure without it. BPs are nocturnal and stay underground most of the day.