Mahapps WPF - Strange behavior with combobox binding

I'm having a strange behavior when I add icons to the ComboBox.ItemTemplate. After initially loading the items, all of them are showing their corresponding icon, but when I select one item, the icon will show in the Combo Part but will disappear in the Expander Part.

You can see the problem here (imgur)

I'm not experienced in WPF/C#, is there something wrong with the way I'm binding the items or the ComboBox.ItemTemplate?

Thanks a lot for the help.-

XAML Code

    <ComboBox x:Name="comboBox" HorizontalAlignment="Left" Height="32" Margin="60,47,0,0" VerticalAlignment="Top" Width="282" ItemsSource="{Binding OtherTasks}" >
        <ComboBox.ItemTemplate>
            <DataTemplate>
                <DockPanel Margin="0" Height="30">
                    <ContentControl Content="{Binding Path=Icono}" Margin="0,4,0,0" Background="Yellow" Width="16" Height="16" Visibility="Visible"/>
                    <AccessText HorizontalAlignment="Stretch" Margin="3,4,0,0" Text="{Binding Path=Text}" TextAlignment="Left" Width="Auto" />
                </DockPanel>
            </DataTemplate>
        </ComboBox.ItemTemplate>
    </ComboBox>

CS Code

namespace test___icon {
    public partial class MainWindow : MetroWindow {

        public class CLASS_OTHERTASKS {
            public string Text { get; set; }
            public object Icono { get; set; }
        }

        public List<CLASS_OTHERTASKS> OtherTasks { get; set; }

        public MainWindow() {
            OtherTasks = new List<CLASS_OTHERTASKS>();
            OtherTasks.Add(new CLASS_OTHERTASKS() { Text = "Test Air", Icono = new PackIconEntypo() { Kind = PackIconEntypoKind.Air } });
            OtherTasks.Add(new CLASS_OTHERTASKS() { Text = "Test Account", Icono = new PackIconMaterial() { Kind = PackIconMaterialKind.Account } });
            OtherTasks.Add(new CLASS_OTHERTASKS() { Text = "Test AxisThree", Icono = new PackIconModern() { Kind = PackIconModernKind.AxisThree } });

            InitializeComponent();
            this.DataContext = this;
        }
    }
}