@mac_ito
We are currently providing the ability to author configurations in Design workspace only. In the Render workspace you can switch between the defined configurations from the browser, but you cant change anything related to configurations there. You should be able to create rendering of different configurations in the Render workspace, using the Local solve. With the cloud solve there is a known problem where render does not pick up the active configuration. We will be resolving this issue, but for now, you can use local solves.
Regards
Gautham
Gautham Kattethota
Software Development