I'm not sure I really understood the problem. :/ I build my Sims in bodyshop then when in game in CAF I pick Existing Sim button and they are there. If I mistakenly created them in bodyshop as a YA they will not appear in the Existing Sim category. I have to go back to body shop, clone that Sim and set their age to the age I want. (game off) Adult Sims created in bodyshop will not appear in the University neighborhood family bins or will not they be available in the University CAF. If that wasn't the answer then sorry I have no idea what the problem is. But correct maybe Maxis should have explained how the game works when creating Sims. But rule of thumb when all reasonable steps fail remove cc.
At this point all I can gather is when you are in bodyshop you don't actually save them or something. Preview is not save.
If you added back in the savedSim file to the game you might need to delete thumbnail packages inside your documents to get the correct thumbnail with the right Sim. Other than the steps you laid out are correct but have no idea what the problem is at the moment other than what I suspect.
