[Ken Case]

Originally Posted by queenofspades

so then please confirm this
- OF defaults to the OmniFocus file in ~/Library/Application Support/OmniFocus/

Yes, that's correct.

- when you open a backup file it saves to that file that has been opened (in backups folder) not the default file. therefore if there's a corruption issue you have to replace the default file with a functional one?

Yes, when you open a backup you're looking at (and editing) that backup, not your main database. (However, any entries you create with Quick Entry will continue to be added to your main database, not the backup, which might explain why you weren't seeing them earlier.)

If you need to restore your main database from a backup, you can select "Revert to Database Backup" from the File menu and then select your backup.