CancellationToken.ThrowOperationCanceledException

I am getting the following error on my Xamarin.Forms project:

  {System.OperationCanceledException: The operation was canceled.
  at System.Threading.CancellationToken.ThrowOperationCanceledException () [0x00010] in <46c2fa109b574c7ea6739f9fe2350976>:0 
  at System.Threading.CancellationToken.ThrowIfCancellationRequested () [0x00008] in <46c2fa109b574c7ea6739f9fe2350976>:0 
  at Xamarin.Android.Net.AndroidClientHandler+<>c__DisplayClass44_0.<ConnectAsync>b__0 () [0x0004f] in 
  /Users/vsts/agent/2.155.1/work/1/s/src/Mono.Android/Xamarin.Android.Net/AndroidClientHandler.cs:343 
  at System.Threading.Tasks.Task.InnerInvoke () [0x0000f] in <46c2fa109b574c7ea6739f9fe2350976>:0 
  at System.Threading.Tasks.Task.Execute () [0x00000] in <46c2fa109b574c7ea6739f9fe2350976>:0 

--- End of stack trace from previous location where exception was thrown ---

  at Xamarin.Android.Net.AndroidClientHandler.DoProcessRequest (System.Net.Http.HttpRequestMessage request, Java.Net.URL javaUrl, 
  Java.Net.HttpURLConnection httpConnection, System.Threading.CancellationToken cancellationToken, 
  Xamarin.Android.Net.AndroidClientHandler+RequestRedirectionState redirectState) [0x000e4] in 
 /Users/vsts/agent/2.155.1/work/1/s/src/Mono.Android/Xamarin.Android.Net/AndroidClientHandler.cs:393 
  at Xamarin.Android.Net.AndroidClientHandler.SendAsync (System.Net.Http.HttpRequestMessage request, System.Threading.CancellationToken 
  cancellationToken) [0x00285] in /Users/vsts/agent/2.155.1/work/1/s/src/Mono.Android/Xamarin.Android.Net/AndroidClientHandler.cs:286 
  at System.Net.Http.HttpClient.FinishSendAsyncBuffered (System.Threading.Tasks.Task`1[TResult] sendTask, System.Net.Http.HttpRequestMessage 
  request, System.Threading.CancellationTokenSource cts, System.Boolean disposeCts) [0x0017e] in <814c177e4f174da89876fafdde15d02e>:0 
  at BUCOLogin.Constants.RestService.GetBranchesAsync (System.String uri) [0x00046] in C:\Visual Studio Training\BUCO FR 
  Login\FacialRecognitionLogin\Constants\RestService.cs:18 }

After some investigation it seems that a token is being cancelled, but I'm not sure where this token is located or even why its being cancelled. I am using an open API request with no APIKey needed :

Constants.cs:

 using System;
 using System.Collections.Generic;
 using System.Text;

 namespace BUCOLogin.Constants
 {
  public static class Constants
  {
    public const string OpenBabbageEndpoint = "HTTP-LINK";
    //public const string OpenBabbageAPIKey = "f6a04a6c3fbc534c295f6a5e8548e0f6";
  }
 }

When stepping through code, it stalls/waits for a while at the following code before giving me the exception:

 HttpResponseMessage response = await _client.Value.GetAsync(uri);

 This code is located in RestService.cs:

 using System;
 using System.Diagnostics;
 using System.Net.Http;
 using System.Threading.Tasks;
 using Newtonsoft.Json;

namespace BUCOLogin.Constants
{
   public class RestService
   {
    static Lazy<HttpClient> _client = new Lazy<HttpClient>(() => new HttpClient());

    public async Task<GetBranches> GetBranchesAsync(string uri)
    {
        GetBranches branchesData = null;
        try
        {
            HttpResponseMessage response = await _client.Value.GetAsync(uri);
            if (response.IsSuccessStatusCode)
            {
                string content = await response.Content.ReadAsStringAsync();
                branchesData = JsonConvert.DeserializeObject<GetBranches>(content);
            }
        }
        catch (Exception ex)
        {
            Debug.WriteLine("\tERROR {0}", ex.Message);
        }

        return branchesData;
     }
   }
  }

GetBranches.cs:

  using System;
  using System.Collections.Generic;
  using System.Text;
  using Newtonsoft.Json;

  namespace BUCOLogin.Constants
 {
   public class GetBranches
  {

    [JsonProperty("name")]
    public string Name { get; set; }

    [JsonProperty("number")]
    public string Number { get; set; }

    [JsonProperty("postcode")]
    public string Postcode { get; set; }

    [JsonProperty("manager")]
    public string Manager { get; set; }

    [JsonProperty("phone")]
    public string Phone { get; set; }

    [JsonProperty("address")]
    public string Address { get; set; }

    [JsonProperty("open")]
    public string Open { get; set; }

    [JsonProperty("close")]
    public string Close { get; set; }

    [JsonProperty("opensat")]
    public string Opensat { get; set; }

    [JsonProperty("closesat")]
    public string Closesat { get; set; }

    }
  }

The uri Request does bring back multiple results on Postman so I am not sure why I am getting this exception and how to move forward.

Thanks in advance.