Puzzling Potty Practices

I am actively asking for advice--I want to say that upfront. I am completely befuddled about what to do, and I welcome any suggestions.

CJ will be 4 in December, and we've been working on potty training for almost a year. We had backed off a bit when it became clear that he had the concept and could control his bladder but was seeing potty training as a control issue. Rather than press the point and come to an impasse, we pointed out the potty, explained that we'd like him to use it, and left it be.

Occasionally, he would go on the potty, but more often he chose his pullup. We tried using daycare as an incentive--we already knew from his teachers that he was in the last room until he was potty-trained and that many of his friends had already gone to the next room. A few weeks, the woman who runs the daycare approached us about moving CJ on into the next room. She explained that she was positive that he could go on his own, but was choosing to be lazy since he could have a pullup changed rather than stop what he was doing. She also felt that since he was nearing four, and many of his classmates had just turned three, that he was too comfortable in his routine and needed the additional mental stimulation (the new room is set up like preschool).

After discussing the pros and cons, we agreed. The transition took place within a week. He's been in the new room for a few weeks and the change is incredible--except for potty-training, and not the way I expected:

He goes without complaint during his time at daycare. He stays dry, goes when prompted, goes on his own, and really seems to love going potty. At home, nope. We put him in underwear and celebrate his successes, but he will usually pee on the floor rather than go to the toilet. Just tonight I've changed three wet pairs of underwear and Tom changed one pair of poopy underwear.

He knows he needs to use the potty--he tells us he peed on the floor instead of going. He doesn't seem to have bladder issues since he can be dry through the night and doesn't have this trouble at daycare.

For whatever reason, he is just refusing to go at home.

We've tried stickers, toys, and books as incentive. I've even offered Dum-Dums. None of it matters. I'm at the end of my rope. I'm trying to be patient like I'm supposed to be for potty accidents, but I really don't think this is about accidents. Part of me wants to enact consequences like I do when he doesn't listen or willfully disobeys in other ways but I don't want him to get mixed signals.

Any suggestions?