[cypher]

I think your biggest problem there is just lack of substrate, you really need to completely fill the base, that might be difficult where the wheel is but you can fence that area off with bendy bridges if need be & fill the rest of the base as much as possible.
You do have a fair bit of stuff in there for him to explore & hideout in but the lack of substrate is making it look very empty & he must feel very exposed while in there.
I would suggest making him a nice house, you can use a cardboard box with no base & just a door cut in, no less than about 15cm maybe 20cm (the house not the door! ) & give him a ton of plain white toilet tissue torn into strips in a pile so he can use it to build a nest if he likes, some of my chinese just burrow into deep substrate under the house while others like the tissue.
They do like to keep the entrance/s to their nest well hidden so given the opportunity will usually make a great big mound of substrate over the door & you will often fine them making little burrow entrances all over the cage!

ETA this is my current HH set up, I usually have hammocks for my Chinese but don't in this one, although it looks quite open there's plenty of hideouts & lots of space to burrow, you can see the big mound outside Zeki's door at the back!

hh.jpg