For anyone still looking for a solution. I had this same problem on my Mac. When I first tried to relaunch the game after not playing in over a year there was a pop up to allow Sims access to my documents folder. I accidentally clicked deny but it never popped up again. This turned out to be the issue.
To fix it:
Go to System Preferences -> Security & Privacy -> Files & Folders -> Find “The Sims 4” in list and tick the “Documents Folder” check box to grant access.
https://www.ea.com/games/the-sims/the-sims-4/news/patch-15655
