If you are sure you are running Duplicati as a service (and started the service using the SYSTEM account or another account with administrative privileges), my guess is that you are running multiple instances of Duplicati.
If you look in the address bar of your web browser, what port number do you see? 8200 or 8300? If it’s 8300, you still use a user based instance with probably limited permissions.
Add --no-hosted-server to the target field of the shortcut to the Duplicati Tray icon to prevent starting up a second, user based instance with tharting up the tray icon.
More info about how to move to a service-based installation can be found here: