As @dot_gitignore said above, the log files are in /Users/xxxx/Documents/Zwift/Logs
You will want to look at “Launcher_log.txt” and see if it offers you any clues.
If you do a reinstall, I would do the following:
- Delete the Zwift launcher from the Dock.
- Go to Applications and delete the Zwift app itself.
- Go to your Documents folder. You should find a Zwift folder. Instead of deleting it, how about you rename it to something like “Old_Zwift” for now. You might want something in it later.
- Empty your trash.
- Reinstall Zwift.
Another option is to launch Zwift directly instead of from the Dock. Go to the Applications folder, right click on the Zwift launcher. I think the English is “Show contents” or something like that. Select that one. Then in the MacOS folder, you will find the “ZwiftLauncher-OSX” executable. Double-click and see if that gives you a different result.
Let us know if any of this helps.