PUT to web api saves update to DB but returns 500 error in HTTPMessageResponse

Consuming web api from mvc controller:

[HttpPost]
public ActionResult Edit(Recipient model)
{
   string svcEndPoint = string.Format("http://localhost:17305/api/recipient/{0}", model.RecipKey);

   using (HttpClient client = new HttpClient(new HttpClientHandler() { UseDefaultCredentials = true }))
   {
      client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
      HttpResponseMessage response = client.PutAsJsonAsync(svcEndPoint, model).Result;

      if (response.IsSuccessStatusCode)
      {
         return View(model);
      }
           else
      {
          return View("Error");
      }
 }
}

Web api:

        public IHttpActionResult GetById(int Id)
        {
            try
            {
                var data = repo.GetRecipient(Id);
                return Ok(data);
            }
            catch(Exception ex)
            {
                return BadRequest(ex.ToString());
            }
        }

It successfully saves edits to the database, but the response.IsSuccessStatusCode is always false. Even though the web api returns the OK message, the MVC client response is 500 internal server error.

I have tried using Fiddler to see what is happening, but I can't figure out how to get it to grab the response from the web api.

I am new to fiddler and not quite sure if this means anything, but it looks like when it first hits, it returns a 401 error, then it goes through. Could this be the issue? 

EDIT:  All my gets are working fine and returning status 200, even though they initially show a 401 in fiddler, so I am thinking that is not it.  

Here is the header value from a PUT:

POST /Recipient/Edit?RecipientId=13971 HTTP/1.1
Accept: text/html, application/xhtml+xml, */*
Referer: http://localhost:22222/Recipient/Edit?RecipientId=13971
Accept-Language: en-US
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko
Content-Type: application/x-www-form-urlencoded
Accept-Encoding: gzip, deflate
Connection: Keep-Alive
Host: localhost:22222
DNT: 1
Cookie: __RequestVerificationToken=Wa8gRZ_K9qubfUjW-6Xe9FzIzpvlIyOvpUexg7pUoQyJllhgCLrdjksDYXD6LbH2OJzUSTLhI-1PlaFxA2rtpa6zVaeD6FIfSRMH4CYdYKw1
Pragma: no-cache
Authorization: Negotiate oXcwdaADCgEBoloEWE5UTE1TU1AAAwAAAAAAAABYAAAAAAAAAFgAAAAAAAAAWAAAAAAAAABYAAAAAAAAAFgAAAAAAAAAWAAAABXCiOIGAbEdAAAAD2mBHrLRKFFkEpDWr0higvGjEgQQAQAAAIU/xffX1AcoAAAAAA==
Content-Length: 306