I am Unable to access the portal feature service which is shared with everyone. I can access the portal item with out using any credentials. But when I access the services from federated ArcGIS server rest end page it is asking for credentials. If I try to verify the sharing permissions in server manager I am getting the error "The service is owned by another user. The sharing properties can only be modified by the owner." But i am the owner of these services and I have published these services. Any help would be much appreciated.
Additional Information: ArcGIS Server version 10.6.1
Single box installation