Not able to see the selected value in the combobox

I'm working on a C#/WPF application.
I'm invoking ProcessServiceResponse() method in MainViewModel on click of a button.
SelectedCountry property value is correctly getting set in this method.The country list combobox is also showing the list of countries.
But somehow, am not seeing a selected value(for e.g. SG) in the country dropdown list.
Any ideas as to what am I missing here please?
Let me know if you need any other details around the code.

Thanks.

Here's my code.

    MainWindow View:
    
    <Window
            xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
            xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:MainViewModel="clr-namespace:MyTool.ViewModels"
            xmlns:ViewModel="clr-namespace:MyTool.ViewModel.Bonds"
            xmlns:View="clr-namespace:MyTool" x:Class="MyTool.MainWindow"
            Title="{Binding DisplayName, Mode=OneWay}" ResizeMode="CanMinimize" WindowStartupLocation="CenterScreen" Height="600" Width="1100">
        <Window.DataContext>
            <MainViewModel:MainWindowViewModel/>
        </Window.DataContext>
    
    
    <ComboBox Margin="1,0" ItemsSource="{Binding MyViewModel.CountryList,UpdateSourceTrigger=PropertyChanged}" DisplayMemberPath="Description" SelectedValuePath="Code" SelectedItem="{Binding MyViewModel.SelectedCountry, Mode=TwoWay}" TabIndex="2" Grid.Row="7"  Grid.Column="2" HorizontalAlignment="Left" Height="23"  VerticalAlignment="Top" Width="180" />
    
    MainViewModel:
    
    public MainWindowViewModel()
    {
    MyAttributes = new MyViewModel();
    
    }
    
    public object MyAttributes
            {
                get { return m_myViewModel; }
                set
                {
                    m_myViewModel = value;
                    OnPropertyChanged("MyAttributes");
                }
            }
    
    public void ProcessServiceResponse()
    
    {
    
       var destination = new MyViewModel();/
                Type destinationType = destination.GetType();
    
                PropertyInfo[] destinationTypePI = destinationType.GetProperties();
    
                string propertyName = string.Empty;
                object propertyValue = null;
    
                foreach (var pinfo in sourcePI)
                {
                    propertyName = pinfo.Name.Trim();
                    var matchingItem = destinationTypePI.ToList().Where(d => d.Name == propertyName);
                    if (matchingItem != null && matchingItem.Count() > 0)
                    {
                        propertyValue = pinfo.GetValue(serviceResponse.lst_DKSecurities[0]);
                        matchingItem.FirstOrDefault().SetValue(destination, propertyValue);                    
                    }
    
                }
                
                this.MyAttributes = destination;
    
    }
    
    MyViewModel:
    
    namespace MyTool.ViewModels;
    public class MyViewModel
    {
    
    public MyViewModel
    {
     this.CountryList = GetCountryList();
    }
    
    public string SelectedCountry
            {
                get
                {
                    return m_selectedCountry;
                }
                set
                {
                    m_selectedCountry = value;
                }
            }
    
    }