Thanks for all the input. I may just have to shelve the idea for now. I have reset everything and all that jazz and done whatever maintenance I could think of. I played the daycare for a day or so to make sure she could take kids in, and she took in the neighborhood toddlers. She even took in the toddler of my original active family, so while the toddler was at the daycare, I switched back to my normal house (where the toddler lives), and lo and behold, he was there, with the same silly problem - hovering over him showed the daycare status, but of course, he was no longer at the day care.

This is only my own experiences here, but I can usually get inactive daycare to work properly for a while -- MC Opening the daycare provider's lot seems to help as that keeps everyone there animated and in a way that I can keep an eye on them. But usually "after a while" (some undefined amount of time) I find that it all breaks down and either kids don't get transported there or I keep getting intrusive messages about a toddler needing to be picked up when I brought them home hours ago already and there are no kids left on the provider's lot.

I usually switch the whole thing off and try again a few sim weeks later when these things start happening. From what I understand the entire structure is slated to be under review when mod development resumes as players' experiences with it are currently not very consistent.