I've found a fix for this through a long time of experimentation (and several death threats aimed at my computer) In a moment of desperation, I tried this, which I used a long time ago when another one of my games glitched.
1. Go into Edit Town mode and save a copy of your family
2. Place them in another house/a copy of their old house (I have not tested if you move them out with their home, but I don't see why it wouldn't work)
3. Begin playing! They will retain everything they had, including degrees, skills, careers, etc. Unfortunately, they lose relationships with the rest of the town, which sucks, but that's repairable.
It worked for me, but I haven't had a chance to test it on another computer. My computer is running Windows 7 (the most recent Windows I can stand using. Windows 8 is a nightmare), and I have some custom content from TheSimsResource, but nothing else that even resembles mods. Good luck to you
-The Oracle Of Quantico