@YorksRobGo 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 not work then we'll try another method later
If it will be work save the game option "Save as .. number " - not "Save and Quit".
I don't work for EA