I don't see any hiding places. Hissers live in rotting logs and near fallen leaf litter in the wild, they must have hiding places to feel safe. At any pet store in Reptile section they sell hollow log decor and branches hissers love to climb and log decor to hide in.
I'm not sure what your substrate is, it almost looks like plant Perlite which is no good. You could use peat moss substrate or I use Repti bark which is safe wood chips treated to be used for animal caging but with cockroaches you must be careful no Pine tree bark is used its dangerous. Better substrate creates some humidity which helps in shedding.
You didn't mention what you feed them but they need a balanced diet. Dog and cat kibble, apple, banana, oranges, mango, papaya, carrots, romaine lettuce, fresh spinach leaves, white bread, cooked beef (plain), as a treat they eat fruit loops cereal. I also spread baby food on white bread for them, flavors they enjoy are banana-orange medley, banana, mango, and once in a while beef or chicken.
Hissers need leaves and wood in their diet. I feed mine old fallen Oak leaves, they are brown and mushy or dry. I also feed decaying tree bark, the kind that is moist and feels like a sponge and falls apart easily, they LOVE leaves and bark and I change the old ones out every 2 weeks.
Also what's your temperature?