Async method is working as syncronous mehtod

Question

I am trying to call a async method of ViewModel from another method in View but it is behaving as syncronous.

View Model:

public async Task<bool> GetReadyForUnlockWithQR()
    {
        try
        {
            SmilaHash = GetRandomeHashKey();
            var data = JsonConvert.SerializeObject(GetSmilaInfo());
            var res = await apiClient.PostAsync<String>("readyforunlockwithqr", data);
            if (res != null)
            {
                JObject json = JObject.Parse(res);
                if (json["doUnlock"] != null)
                {
                    LoginStatus = json.SelectToken("doUnlock").Value<bool>();
                }
            }
        }
        catch (Exception ex)
        {
            Debug.WriteLine(ex.Message);
            CancelPendingRequests();
            throw ex;
        }
        return false;
    }

I have my api methods defined in a custome APIClient file. The above request may take a minute to complete. I don't want to stop the UI and perform my further operations in View. Following is my View:

private async void UnlockButton_Click(object sender, RoutedEventArgs e)
    {
        try
        {
            await ViewModel.GetReadyForUnlockWithQR();
            DisplayQRCode();
        }
        catch(Exception ex)
        {
            if (ex is HttpRequestException)
            {
                Debug.WriteLine("Server not reachable");
                MessageBox.Show("Server not reachable");
            }
            else if (ex is OperationCanceledException)
            {
                Debug.WriteLine("Timeout exception");
                QRCodeImage.Source = null;
                QRCodeCanvas.Visibility = Visibility.Hidden;
            }
            else
            {
                Debug.WriteLine(ex.Message);
            }
        }
    }

I above code ideally the DisplayQRCode() function should work immediately after await ViewModel.GetReadyForUnlockWithQR(); but it is not happening. The DisplayQRCode() is waiting to receive response from ViewModel.GetReadyForUnlockWithQR() Why is this not behaving as logical asyn code.