So far I've only found 1 fix, but it will cost you LP. I gave my blacked-out Sim an ultimate makeover (2 LP) and changed his gender. The new female Sim had regular skin, and I exited CAS. Then I immediately gave the "new" Sim an ultimate makeover (another 2 LP) and changed the gender back to male. The skin was normal again but I had to reassign his features and clothing, hair, etc. Then I saved the game to the cloud and exited. When I reopened the game, my Sim was still normal.
I had 2 Sims that blacked out and this worked on both of them. Just remember to make note of your Sim's hair, clothing, and features so you can rebuild it when you switch back.
Thank you
