Eco earth isn't a good substrate for leos, it's used for 'forest' reptiles to keep the humidity up. Something that you don't want to do for leos. Also if you're using a mat, it'll have a tough time getting to the correct temperatures.
4ft viv is quite big for one leo. It's fine however it will need more than 3-4 hides, it may be that it feels safer in the cool end if it's more covered or got a better hide in that end.
Is he eating? What heating are you using (bulb or mat)? How are you measuring your temperatures? And do you know what the exact temperatures are?