I have my sims family where the two kids are getting ready to age to YA. I was looking around searching for the kids of townies who should have aged up, and several seem to still be at the age they were when I started the town. Leighton Sekemoto at the start has a toddler son, Sam. This was before my sim had married Conner, so Sam should be at the least a teen, and really should be a YA. Yet when I had one of my sim kids visit the house, Leighton looked the same and there were baby items, there were three bedrooms, with one still having a crib and such in it.
Some of the older ones, such as Nick Vito (not sure of last name) has died, but Alva and Holly are still alive. Holly looks the same but she is now in law enforcement; at the start she was a teen still in school.
With some, you can tell the kids have aged up, no longer children but now teens, the adults it is hard to tell, they could be at the end of their adult and not aged up to elder. It is the younger that has me confused. Some who were toddlers or a child, such as Sam, should at least now be teens, but seem to still be children.
I haven't changed anything in story progression and have changed the aging length, but still, those townies should age as my sim and her kids have.
The only expansion packs I have are WA and Pets.