[cypher]

It does sound as though he may just be enjoying burrowing in his substrate, if you can post a photo of your set up though it would help to see if maybe you could change anything to encourage him to come out more.
You could try scatter feeding & hiding food and treats around the cage so he can forage naturally & not just grab some from the bowl & disappear. As he’s used to a food bowl I would do both for a while so as not to stress him out if his bowl suddenly vanished.