Custom fields not showing correctly in Document Template

We are trying to submit a Service Request and take information from the service request into a document template via fields to produce the document.

The fields are defined by example as {{Parent}} and {{Child}}.
We are able to map the fields correctly for some item such as {{}} but my custom fields from the Service Request are not being filled in automatically for the document preview.

Here is the struggle:

  1. Create/redraft the letter with the placeholders.
  2. Create a document template.
  3. Create a service item.
  4. Select “Document” under Service Item Settings on the new service item page.
  5. Use the document template as a document in the new service item.
  6. Map the fields.
  7. Save and publish.
  8. Request the same item by using the service desk.
  9. You will be taken to the service request, #SR0596 example.
  10. Press the generate button to see the filled-in template.
    11 But not all of he fields are getting filled in to pass on to the template

When I generate an SR, the names of the fields are not all coming through to the agent side to be filled into the template.

Has anyone used custom fields in a Document template and been successful? I know it should work, but what are we doing wrong.

Anyone even doing documents in Assets?