The Sims 4 - December 2019 Update + Mods

@roxxi868It's all in how you do it.

What happens is this: When you play the game and use CC hair, clothes and such, the sims are tagged as using those CC items.

As you've seen, when your game updates, mods and CC are disabled.

If the mods and CC are disabled, and you load your game and SAVE it, any sim that had CC will have it removed. Thus all your sims will be naked and bald.

If you then enable CC/Mods, your sims will still be naked and bald. It's too late. Once you've saved your game with the CC disabled, the CC is REMOVED from your sims. Re-enabling CC isn't going to bring it back.

If you've already saved while CC was disabled, unfortunately there's nothing you can do. You can either use an older save (if you have one) or go through every single sim and re-apply the CC one by one... which is a huge pain.

The best way to handle updates is this: If your game updates, boot up the game, get to the first menu and DO NOT load a save! Go straight into the options screen, re-enable mods and CC, and exit.

Once you re-load, your sims should be good.

What @EuphorialQueen mentioned is the best way to handle it. I always have automatic updates disabled, that way I KNOW when there's an update. That way I can update, go to the main screen, re-enable mods/cc, and exit without ever loading a save and possibly corrupting my saves like you've seen.