Adding Anchor tags to a document

I have been hitting a bit of a brick wall trying to add text anchor tags to an uploaded document. Let my explain what I have been attempting to achieve. First I upload a document to an existing package, the package already contains a new role that I have created. Both the package and the role are created though the sandbox web interface just to bootstrap the environment. I then progmatically upload a document with the following details for example I POST a multipart request to https://sandbox.esignlive.com/api/packages/f7d04bb5-f9df-4d7a-95d7-50f84a7ebb4f/documents. note: I would swap the :id to what ever new package I had created to work with. This uploads find a returns a successful response like following:

{
         "status": "",
    "description": "",
      "approvals": [],
          "pages": [
         {
                "top": 0.0,
             "height": 1030.0,
               "left": 0.0,
              "width": 796.0,
                 "id": "2bbb4929f5561c75_1.png",
              "index": 0,
            "version": 462978
        }
    ],
       "external": nil,
        "extract": false,
             "id": "a8eeb13740979ff9",
           "data": nil,
          "index": 1,
         "fields": [],
           "name": "test_form",
           "size": 6466
}

I then perform a GET request just to confirm to document is there. I know this step is not really needed, but I'm just trying to break it down while I'm trying to debug. I take the name and index from the response and use them to create the following request payload for a PUT request

{
  "name": "test_form",
  "index": 1,
  "approvals": [
    {
      "fields": [
        {
          "type": "SIGNATURE",
          "width": 200,
          "height": 50,
          "page": 0,
          "extract": false,
          "extractAnchor": {
            "text": "Nondisclosure",
            "index": 0,
            "width": 150,
            "height": 40,
            "anchorPoint": "BOTTOMRIGHT",
            "characterIndex": 9,
            "leftOffset": 0,
            "topOffset": 0
          },
          "left": 0,
          "subtype": "FULLNAME",
          "top": 0
        }
      ],
      "role": "Signer1"
    }
  ],
  "extract": true
}

This would give me the following response.

{
     "packageId": nil,
    "messageKey": "error.validation.packageManagement.invalidDocument",
     "technical": "Document: c320a4f84cc9c938 was not found for Process with Guid: f7d04bb5-f9df-4d7a-95d7-50f84a7ebb4f",
        "entity": nil,
          "code": 404,
       "message": "Can not find specified document.",
          "name": "Resource Not Found"
}

If I remove the index key from the original PUT request, I get a successful response, but the role isn't assigned and sandbox web UI for that pack will crash with and error in the console about a missing role. I can get the package to load in the web UI again if I make a DELETE request to the api and remove the affected document. I'm at a bit of a loss as where to go from here.