@Cerulean_Bead Where is Sims 3 currently installed? For example, is it in Applications, Users > your username > Applications, or a custom location? And where is the EA App's default install directory? You should be able to see it under Settings > Installs, or something similar.
Both are in their default locations. EA App in Applications, Macintosh HD > Applications. The Sims 3 is in Macintosh HD > Applications > EA Games. I know that before, with Origin, The Sims 3 was being installed under Users > My Username > Applications, but now the default location has been changed for EA App.
@Cerulean_Bead I was actually asking what location the EA App lists for your game library, and whether that's different than the location where Sims 3 is installed. The EA App itself has an "Installed Games" (or similar) section of settings where you can choose the location of your game library, and I wanted to know whether that matched the location where Sims 3 is installed. It sounds like they do match, but please double-check and let me know if that's not the case.
Do you use a third-party antivirus, a cleaner app, or a VPN? Any of these could be triggering the issue and would explain why reinstalling the game didn't help. If so, please disable or remove the program in question, then repair Sims 3 again and see whether you can play.
@Cerulean_Bead A couple of players with a similar issue with Sims 4 had to add the game to Full Disk Access. So please try that too: open System Settings > Security & Privacy, click the lock to make changes and enter your password, click Full Disk Access on the left, and add Sims 3 on the right.
