That looks like a valid Windows path to me, so I don’t think that’s the issue.
If you go into the now working / non-customized dbpath job and use the Database link it should take you to a page with database maintenance type buttons on it.
Try changing the “Local database path” field to where you want the database to be stored then clicking the “Move existing database” button. Does that work (yay) or give you an error (perhaps the account Duplicati is running under doesn’t have permission to your “Secure” folder)?