Have you put moss everywhere on the floor of the tank or just in his moist hide?
Leos need 3 hides: warm dry, warm moist, and cool dry.
What temperatures are you providing?
Temperatures for all leos regardless of size:
88-93 F (31-34 C) ground temp at warm end inside the warm dry hide
no greater than 85 F (29.5 C) air temp - 4 inches above ground on the warm end
no greater than 75 F (24.5 C) air temp - 4 inches above ground on the cool end
Leave the UTH on 24/7. Can turn off overhead heating at night.
There are many, many details in the caresheet, all of which a leo owner needs to be aware of.