VS2019 Adding Connected Service via OpenAPI not generating all required classes

Question

We have a swagger generated OpenAPI definition which has an endpoint that defines it's responses as the following:

"responses": {
  "200": {
    "description": "Success",
    "content": {
      "text/plain": {
        "schema": {
          "type": "file"
        }
      },
      "application/json": {
        "schema": {
          "type": "file"
        }
      },
      "text/json": {
        "schema": {
          "type": "file"
        }
      }
    }
  }
}

When using NSwagStudio to generate a C# Client from swagger.json, the response type translates into a class which gets defined into the generated file like so...

NSwagStudio Generated Endpoint example

public System.Threading.Tasks.Task<FileResponse> FileAsync(LayeredVideo body)
{
    return FileAsync(body, System.Threading.CancellationToken.None);
}

NSwagStudio Geneated FileResponse class

[System.CodeDom.Compiler.GeneratedCode("NSwag", "13.15.10.0 (NJsonSchema v10.6.10.0 (Newtonsoft.Json v12.0.0.0))")]
public partial class FileResponse : System.IDisposable
{
    private System.IDisposable _client;
    private System.IDisposable _response;

    public int StatusCode { get; private set; }

    public System.Collections.Generic.IReadOnlyDictionary<string, System.Collections.Generic.IEnumerable<string>> Headers { get; private set; }

    public System.IO.Stream Stream { get; private set; }

    public bool IsPartial
    {
        get { return StatusCode == 206; }
    }

    public FileResponse(int statusCode, System.Collections.Generic.IReadOnlyDictionary<string, System.Collections.Generic.IEnumerable<string>> headers, System.IO.Stream stream, System.IDisposable client, System.IDisposable response)
    {
        StatusCode = statusCode;
        Headers = headers;
        Stream = stream;
        _client = client;
        _response = response;
    }

    public void Dispose()
    {
        Stream.Dispose();
        if (_response != null)
            _response.Dispose();
        if (_client != null)
            _client.Dispose();
    }
}

however if I attempt to generate the same C# client within VS2019 via the Connected Services interface while the endpoint itself generates the same, it does not define the actual FileResponse class

VS2019 Generated Endpoint example

public System.Threading.Tasks.Task<FileResponse> FileAsync(LayeredVideo body)
{
    return FileAsync(body, System.Threading.CancellationToken.None);
}

This leads to the following error in the generated code.

By my understanding, NSwagStudio and Connected Services use basically the same tech in the background to generate code, so I am confused as to why one solution generates working code and the other doesn't.

Any ideas?