Have you double checked that your game is on Normal speed?
You mean speed 1? I often am on that. If you mean Aging, I am most definitely, 109% on Normal Length.
Double check your game clock to see the week you're on.
At the last check, Week 12, Day 5. I'm probably now in Week 13.
Are your Sims aging normally?
Yes.
What method are you using to determine those townies are still Young Adults?
Because of Dynasty rules, I'm doing it by looks. They look exactly the same as if you were to load up Riverview for the first time. I am also certain that the vast majority aren't vampires.
How old are they supposed to be?
Dead. A teenager has died before them (MaryKay Shallow just died of old age.)
I'm also not sure if this is related, but my 2nd Generation temporarily vanished off the map, and appeared about 10 SimKilometres off of it. As if she was in France. The last time I travelled was quite a while ago.
EDIT: Would I be allowed to switch households for a moment and check if someone's drunken Age Freeze?