I have tried to offer bugs. He just ignores them. He'll wiggle his tail but won't strike. I even tried pulling the head off a cricket and pupae to see if he would eat it. No luckIt's very likely the poop is due to the critical care since it's a puree. If you hold your gecko and push a bug at its mouth will it try to eat it? If you haven't tried that, try it soon because that's a lot closer to a "normal" diet.
Aliza