如何更改组合框显示但不重视

Question

我遇到问题，当我尝试更新我的组合框选项的显示值时，它不会更新显示的所选选项。我保持它返回的相同值，只需更改该选项的显示值即可。有没有办法做到这一点？

一些视图模型：

public class NestedViewModel : ViewModelBase
{
    #region Fields

    private ToneAction selectedValue;
    private Collection<KeyValuePair<string, SomeEnum>> options;

    #endregion

    NestedViewModel(){
        var newOptions = new Collection<KeyValuePair<string, SomeEnum>>();
        foreach (SomeEnum e in Enum.GetValues(typeof(SomeEnum)))
        {
            newOptions.Add(new KeyValuePair<string, SomeEnum>(Random.Next(), e));
        }
        vm.Options = newOptions
    }

    public SomeEnum SelectedValue
    {
        get { return selectedValue }
        set
        {
            if (selectedValue == value)
            {
                return;
            }

            selectedValue = value;
            RaisePropertyChanged(nameof(SelectedValue));
        }
    }

    public Collection<KeyValuePair<string, SomeEnum>> Options
    {
        get { return options; }
        set
        {
            if (options == value)
            {
                return;
            }

            options = value;
            RaisePropertyChanged(nameof(Options));
        }
    }

    #endregion
}

ViewWithComboBox.xaml

<ComboBox Grid.Column="1" 
    ItemsSource="{Binding Options}"
    SelectedValuePath="Value"
    DisplayMemberPath="Key"
    SelectedValue="{Binding Path=SelectedValue}"/>

some service.cs

public class SomeService{
    var vm = new NestedViewModel();
    vm.SelectedValue = options.Last().Value; //updates and display key in combo box correctly

    var newOptions = new Collection<KeyValuePair<string, SomeEnum>>();
    foreach (SomeEnum e in Enum.GetValues(typeof(SomeEnum)))
    {
        newOptions.Add(new KeyValuePair<string, SomeEnum>(Random.Next(), e));
    }
    vm.Options = newOptions; //sets combo highlighted red and blank

    vm.SelectedValue = options.First().Value; //updates and display key in combo box correctly
}