Unable to bind `Glyph` property in `FontImageSource` of `ToolbarItem`

Description

Original discussion: https://forums.xamarin.com/discussion/180852/why-glyph-property-in-fontimagesource-doesnt-bind
Xamarin issue: https://github.com/xamarin/Xamarin.Forms/issues/12700

This code doesn't produce any errors, but Glyph is always empty:

<ContentPage.ToolbarItems>
    <ToolbarItem IconImageSource="{FontImageSource Glyph={Binding MyIcon}, FontFamily=MaterialDesignIcons}" />
</ContentPage.ToolbarItems>

Static binding works fine. Code above also works if it's added via Hot Reload (but after proper app reload icon is gone again)

Steps to Reproduce

1. Add ToolbarItem to your page
2. SpecifyIconImageSource to it as FontImageSource with binded Glyph

Link to public reproduction project repository

Remove the converter and start the app:
https://github.com/maxkoshevoi/NureTimetable/blob/5f67cadbb78bc3c37df4985adf8c4ce3a936b4a0/NureTimetable/UI/Views/Timetable/TimetablePage.xaml#L20

Version with bug

6.0.486 (current)

Last version that worked well

Unknown/Other

Affected platforms

Android

Affected platform versions

All (tested on 13)

Did you find any workaround?

Thanks Saskia.

<ToolbarItem IconImageSource="{Binding MyIcon, Converter={converters:ToolbarIconValueConverter}}" />

public class ToolbarIconValueConverter : IValueConverter, IMarkupExtension
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return new FontImageSource
        {
            FontFamily = (OnPlatform<string>)Application.Current.Resources["MaterialFontFamily"],
            Glyph = (string)value
        };
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }

    public object ProvideValue(IServiceProvider serviceProvider)
    {
        return this;
    }
}

Relevant log output

No response

Start with the linked reproduction project and the ToolbarItem declaration in TimetablePage.xaml around line 20. Run the Android app after removing the converter, then compare the direct FontImageSource binding with the converter workaround. Done means the bound Glyph displays after a normal app reload without the converter.