[itsme]

I manage my library myself and it works fine, see
https://www.zubersoft.com/mobilesheets/f...-8144.html
https://www.zubersoft.com/mobilesheets/f...-8767.html
https://www.zubersoft.com/mobilesheets/f...10834.html

My files are in GoogleDrive, Google's "Drive for Desktop" syncs scores and fakebooks between my Windows devices.
On my Android devices I sync scores and fakebooks with FolderSync Pro https://play.google.com/store/apps/detai...rsync.full between GoogleDrive and the MobileSheets storage location that I specified.
All scores and fakebooks are in an identical (relative) folder structure inside the MobileSheets storage location on all devices.
I maintain MobileSheets database(s) on a Windows device and copy them manually to other devices, both Windows and Android, where I want to use them. As paths are stored as relative paths within the database copying works fine between Android and Windows, I never tried Apple devices.
I make frequent backups of my scores and fakebooks folder/subfolder tree and of C:\...\ 41730Zubersoft.MobileSheets_ys1c8ct2g6ypr\LocalState
I do not use the MobileSheets sync features.

@Mike: you wrote
Just don't uncheck the "Let MobileSheets Manage my Files" in the Android version if you want to seamlessly move the database file between versions without relying on the built-in backup or sync features.
Is that a typo? On my Android devices "Let MobileSheets Manage my Files" is OFF to work as described.