It sounds to me like there may be an issue with restoring a backup file and then immediately using the "Find Missing Files" feature. The fact that you restarted the app and got different results makes me think that... I'll have to try that out myself. As far as the database, I completely delete the file and create a new instance of the class that manages all the library data, so I'm not sure how there could be anything surviving in a cache. You are correct that 2.3.0 has the change to no longer try to strip out numeric prefixes for MobileSheetsPro backup files.
Mike
Mike