I'm going through the exact same thing! Holden was at his babysitter's while I was away, and when I brought him home there was no poop on his wheel. I did the flour thing too and he is going on it, but I'm not sure for how long. He is also pooping at his food and water dish
which is very close to his litter box. I brought him to the vet and he got a clean bill of health so I am still confused.