Using "My Passport 4TB" with "WD Backup" - No backup is done for "Cryptomator" Drive

All my personal data is stored on “Microsoft OneDrive”.
Some of my data is not encrypted, some is encrypted.

For encryption I use Cryptomator. Cryptomator creates from the encrypted data in OneDrive a virtual drive, on which I can access my decrypted data.

Using “My Passport 4TB” with software “WD Backup” works fine for the not encrypted folders of OneDrive. But it does NOT backup the decrypted data from the virtual Cryptomator drives.

Is there any reason why this does not work?

Some WD drives does not support third party applications. Hence, first you should bar the third party app services and then backup the data via WD backup S/F.