WPF MVVM ComboBox SelectedItem or SelectedValue not working

Question

Update

After a bit of investigating. What seems to be the issue is that the SelectedValue/SelectedItem is occurring before the Item source is finis

Answer 1

You can also bind your SelectedIndex to a property in your ViewModel and manipulate your SelectedItem that way:

        public int SelectedIndex
        {
            get { return _selectedIndex; }
            set
            {
                _selectedIndex = value;
                OnPropertyChanged();
            }    
        }

And in your XAML: