I solved my problem. I had the duchess escape via household management with the baby to a manor nearby, owned by the duke. Then I entered the manor and the baby was there, probably reset by the moving. So I managed to age it up from baby to infant before returning them to the main estate.
It still feels a tad wonky though. I really hope this might be a baby thing, and will not happen to my many infants and toddlers while I'm out and away on my rotation journey...
Glad you solved it, but wow, I'd be hopping mad myself. That's positively deplorable. I had one of my Sims go visit her brother who had just had triplets. I found all three of them wailing away, so the Auntie, did was most would do. She stayed long enough to feed them.
I do hope this was just some kind of glitch, else, you're quite correct, rotational play has just been kicked to the curb. Yikes.
