The Root Admin cannot see all or some the hosts that have been deployed with another user or admin. You have checked the documentation and settings but still fail to get the Root Admin to display the hosts. Furthermore, the Database Console nsi_devices table lists the hosts seen by the users.
This is by design and there is no setting which will allow you to see the hosts.
You may notice a setting “Allow User to see the Completed Scans and Single Host Agents from all other Users”. This setting is for the user or admin to share the scan results with other users and admins. It will not share the data with the Root Admin.
If you have partially deployed the SVM Agent with the Root Admin, depending on the account setting above, then the other users may be able to see the hosts.
Please get in touch with SVM Support and we will discuss available options with you should you wish for the Root Admin to see all the hosts.