@Riko_CornuetLooks like this sim file is damaged. Maybe save him to the library and start a new game with him to check if in the new save you will have the same trouble with him. "Save as" this game - so you will be able to delete this new save.
This way below may not help in this situation, but you can try it.
Go to your game folder /user/Library/Documents /Electronic Arts - inside will be The Sims4 folder.
Find the file localthumbcache.package - and delete it. Don't be afraid. The game will create a new one but without saved errors.
Next, go to the Origin and fix the game,
Origin/Library - right click on TS4 - option "Repair game"
You have to wait until Origin will fix all packs, not only the base game.
If it will be work save the game option "Save as .. number " - not "Save and Quit".
I don't work for EA
