AppBarButton exceptions in Windows 8.1

MainPage.xaml

<Page x:Class="BlankApp1.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">

    <Page.Resources>
        <!-- this works -->
        <Style x:Key="Style1" TargetType="AppBarButton">
            <Setter Property="Icon" Value="Previous" />
        </Style>
        <!-- these throw exception -->
        <Style x:Key="Style2" TargetType="AppBarButton">
            <Setter Property="Icon">
                <Setter.Value>
                    <SymbolIcon Symbol="Previous" />
                </Setter.Value>
            </Setter>
        </Style>
        <Style x:Key="Style3" TargetType="AppBarButton">
            <Setter Property="Icon">
                <Setter.Value>
                    <FontIcon Glyph="&#x1F4BF;"/>
                </Setter.Value>
            </Setter>
        </Style>
    </Page.Resources>

    <Page.BottomAppBar>
        <CommandBar x:Name="Bar" IsOpen="True">
            <CommandBar.PrimaryCommands>
                <AppBarButton Style="{StaticResource Style1}" Label="Style1"/>
                <AppBarButton Style="{StaticResource Style2}" Label="Style2"/>
                <AppBarButton Style="{StaticResource Style3}" Label="Style3"/>
            </CommandBar.PrimaryCommands>
            <CommandBar.SecondaryCommands>
                <AppBarButton Icon="Previous" Label="NoStyle1"/>
                <AppBarButton Label="NoStyle2">
                    <AppBarButton.Icon>
                        <SymbolIcon Symbol="Previous" />
                    </AppBarButton.Icon>
                </AppBarButton>
                <AppBarButton Label="NoStyle3">
                    <AppBarButton.Icon>
                        <FontIcon Glyph="&#x1F4BF;" />
                    </AppBarButton.Icon>
                </AppBarButton>
            </CommandBar.SecondaryCommands>
        </CommandBar>
    </Page.BottomAppBar>
</Page>