How do I add custom content fields to content types in Open Social?

I am trying to add fields to my new custom content type in Open Social (OS), the Drupal social networking distribution. I follow the regular procedure of adding a new custom content type from /admin/structure/types/add. OS will add the custom content type fine, but then after the new content type is created, the list of content types at /admin/structure/types shows only Edit or Delete operations in the combo box for the operations, with Edit being the default. Normally, there are possible operations of Manage fields, Manage form display, and Manage display as well in the combo box for the operations. Furthermore, when I use the normal path for adding a custom field for the content type, namely /admin/structure/types/manage/<content type>/fields where <content type> is the content type I just created, I get an error message of The requested page could not be found. OS exhibits the same behavior for existing content types like Topic. I have found this to be the case for version 8.7.8 and 8.8.10 of OS.

Does anyone know how to enable to ability to add and manage custom fields for new content types in Open Social?