swagger is not rendering requestbody

I have the following openapi 3.0 compliant yaml file which I am trying to render via swagger. There are no errors reported in the yaml file, but the requestBody is not rendered on the swagger GUI. I just get a parameters field which is empty but nothing rendered for the request body, nor do I get any errors. Screenshot below.

paths:
  /my-api:
    post:
      summary: My API Summary
      description: My API Description
      tags:
        - Cost Center
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              properties:
                data:
                  type: array
                  items:
                    $ref: '#/components/schemas/ReqBodyStruct'

What is the way to get the RequestBody also shown in the swagger gui ? Do I miss something ?