Async request never ends using RestSharp

Question

I'm using RestSharp to do a GET request Asynchronously but it never ends. If I do the same request Synchronously it ends successfully. I have used RestSharp just like this before and it always worked.

What am I doing wrong?

Here's the async method: (this.Client is just localhost)

public async Task<ServiceResponse> UpvoteArticleAsync(string source, string url)
{
    var client = this.Client;
    var request = new RestRequest("service/upvote/"+source+"/"+url, Method.GET) { RequestFormat = DataFormat.Json };
    var cancellationTokenSource = new CancellationTokenSource();
    var deserial = new JsonDeserializer();

    var response = await client.ExecuteTaskAsync(request, cancellationTokenSource.Token);

    return deserial.Deserialize<ServiceResponse>(response);
}

and this is how I call it:

ServiceResponse result = await rest.UpvoteArticleAsync (this.article.Source, this.article.Url);

As I said if I change the async method to a sync one, it works:

public async Task<ServiceResponse> UpvoteArticleAsync(string source, string url)
{
    var client = this.Client;
    var request = new RestRequest("service/upvote/"+source+"/"+url, Method.GET) { RequestFormat = DataFormat.Json };
    var cancellationTokenSource = new CancellationTokenSource();
    var deserial = new JsonDeserializer();

    var response = client.ExecuteTaskAsync(request, cancellationTokenSource.Token);

    return deserial.Deserialize<ServiceResponse>(response.Result);
}

EDIT:

I used try and catch to see if there's any exceptions but it didn't throw any.

EDIT 2:

Even if I do the same request with HttpWebRequest from System.Net it still gets stuck when using the async version of GetResponse:

public async Task<bool> UpvoteArticleAsync(string source, string url)
{
    var request = HttpWebRequest.Create(string.Format(@"http://192.168.43.199:8080/service/upvote/{0}/{1}", source, url));
    request.ContentType = "application/json";
    request.Method = "GET";

    using (HttpWebResponse response = await request.GetResponseAsync () as HttpWebResponse)
    {
        if (response.StatusCode != HttpStatusCode.OK)
            Console.Out.WriteLine("Error fetching data. Server returned status code: {0}", response.StatusCode);
        using (StreamReader reader = new StreamReader(response.GetResponseStream()))
        {
            var content = reader.ReadToEnd();
            if(string.IsNullOrWhiteSpace(content)) {
                Console.Out.WriteLine("Response contained empty body...");
            }
            else {
                Console.Out.WriteLine("Response Body: \r\n {0}", content);
            }
        }
    }
    return true;
}