Corns do burrow a lot. Young ones like the nice tight areas to hide in. I'm just curious, what size tank do you have him in? How long have you had him? Is he real little or an adult?
You could change to a paper substrate, but he may just decide to hide out in one of the hides.
He may just need a little time. I know you want to see him, but he may not be quite ready, yet.
Wayne