FlipView Banner only showing default value when using DataTemplate

[JKamsker]

Describe the bug

The FlipView control in MahApps.Metro is ignoring the BannerText property of the FlipViewItem. Regardless of whether BannerText is set to an empty string, a non-empty string, or bound to a property, the text "Banner" is always displayed.

Steps to reproduce

1. Create a new WPF project.
2. Install the MahApps.Metro NuGet package.
3. Add a FlipView control to the main window.
4. Set the ItemTemplate of the FlipView to include a FlipViewItem with BannerText="", BannerText="SomeText", or BannerText="{Binding SomeProperty}".
5. Run the project and observe that the "Banner" text is displayed, regardless of the BannerText setting.

The code in the ItemTemplate is as follows:

<mah:FlipView.ItemTemplate>
    <DataTemplate>
        <mah:FlipViewItem
            BannerText=""
            BorderThickness="0"
            Foreground="White">
            <Image
                HorizontalAlignment="Stretch"
                VerticalAlignment="Stretch"
                Source="{Binding ImageSource}"
                Stretch="Fill" />
        </mah:FlipViewItem>
    </DataTemplate>
</mah:FlipView.ItemTemplate>

Expected behavior

The FlipView control should respect the BannerText property of the FlipViewItem. The text displayed should match the value of BannerText.

Actual behavior

Regardless of the BannerText setting, the text "Banner" is always displayed.

Mitigation

Set IsBannerEnabled to false in FlipView and do it myself if i need it

Environment

MahApps.Metro version: 3.0.0-alpha0457
Windows build number: Win10 22H2 
Visual Studio: 2022 17.8.3
Target Framework: .Net 8.0-windows

Screenshots