Ideas
Same here. Mine was a Cupid's Corner Gallery Creation whom I invited to join the family in play. I changed her name and gave her new outfits. In CAS, my new outfits are shown. In Sims life she wears the old clothing. Clicking on "change outfit" does nothing, the old outfits are shown. Sometimes she changes into the new outfit after a shower Woo Hoo. She also has changed into the new outfit from the towel after showering in a gym. I have now created a new household with her, changed her name again, and moved her into a new lot, but she is still wearing the old clothing although CAS shows otherwise. I hope I have helped with my additional information.
I forgot to add that the Sim in question keeps the old clothes on when she showers or takes a bath.