It appears that the 'administrator (TA)' role cannot create/modify elements (management modules, metric groupings, universes, etc.) in the instance.
Per engineering, the role ‘Tenant Administrator (TA)’ from the Customer Tenant is causing confusion.
Release : SAAS
Component : APM SAAS ENTERPRISE
Engineering has removed the confusing role ‘tenant administrator (TA)’ from the Customer Tenant.
And updated the Customer Accounts to Tenant Administrator, any of the tenant administrators on this tenant can manage/control the user management further as needed.