Combobox Not Updating Despite SelectedItem and ItemsSource Bindings
uwp add tag
Hosch250 (imported from SE) 
I have the following ComboBox:



    <ComboBox SelectedItem="{Binding SelectedTheme, Mode=TwoWay}"
              ItemsSource="{Binding Themes, Mode=OneTime}" />

It is bound to the following values in my VM:



    private Theme _selectedTheme;
    public Theme SelectedTheme
    {
        get { return _selectedTheme; }
        set
        {
            if (_selectedTheme != value)
            {
                _selectedTheme = value;
                OnPropertyChanged();
            }
        }
    }

    public List<Theme> Themes =>
        Enum.GetValues(typeof(Theme)).Cast<Theme>().ToList();

I set `SelectedTheme`s value in the VM's ctor, and the `get` member is being hit after I assign the VM instance to my `Page`'s `DataContext`.  My trouble is the UI does not reflect the binding value the first time I load the page; it updates works correctly all other times, but the combobox does not show any selection after the page is initially loaded.
Top Answer
Hosch250 (imported from SE) 
After struggling with this issue for about two hours, I realized that the UWP framework is connecting the bindings in the order they are set, so the `SelectedItem` is being set correctly, but is then cleared when the `ItemsSource` value is set.  Changing my XAML to the following fixes the problem:



    <ComboBox ItemsSource="{Binding Themes, Mode=OneTime}"
              SelectedItem="{Binding SelectedTheme, Mode=TwoWay}" />
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