New BP Won't Use Hide

I picked up a 200g Bumblebee on Sunday. Set up his cage the day before (28x24x12 Vision V221) that is more or less identical to my other BP set up. I'm usingusing ZooMed heat cable and his hot sideside stays around 89 with the cool side being 80. I have hides on both sides but admittedly they are a bit big for him (posted about this the other day and people said crumpling up newspaper inside to reduce space was ok). There's a large water bowl, and a few decorations as well. Humidity floats between 50-70 depending on when I last misted the enclosure.

My 600g BP with essentially an identical set up loves it. Healthy as can be, eats every 5 days, sheds in one piece, etc. But the new guy doesn't seem so happy. He was in a small enclosure with 3 other snakes, so I'm thinking it's a big adjustment for him. He curls up behind his cold hide in the corner, and will not go into his hides.

He doesn't roam the cage during the day so I know he's not too hot or uncomfortable. But why won't he use his hides? My other snake went straight into his the day I brought him home and never had a second thought. Thanks for your help!

(on mobile, sorry if there's formatting errors)

Do you know what kind of substrate he was on before?

I had a similar issue with a ~700g girl going into a 32qt tub. She wouldn't use the hide, refused to eat, and seemed very nervous. I got a smaller hide and put her on aspen (I normally use paper towels) and the change was amazing. I had tried crumpled paper towels first, but I think she preferred feeling more snug - paper towels and newspaper are too light for that. It's kind of like the difference between sleeping under only a sheet versus a heavy quilt. Which one feels like it would better protect you from monsters under the bed? I think crumpled paper is best used to clutter up the rest of the tank by reducing their line of sight.

If you're not able to use a substrate, add a lot more crumpled newspaper or you could try keeping a wash cloth or dish towel in the hide. You could also try a smaller hide - a small black takeout container with an opening cut into the side would be fine, and doesn't break the bank.