I've got two attempts going right now with a similar bug. In one, the now YA heir has a boyfriend that has been a teen since she was a child, and in the other I have am elder in my household who, despite saying he is 92 days old, the bar is not filling in.
In the first, I was wondering if it would be okay to age up the teen, since he has stopped aging entirely. In the other, I'm not sure what to do, my second gen is only a child, but it seems cheatsy to have a sim that won't age in my household.