ToolbarItem Effect for custom font

I am attempting to create an effect that will style the ToolbarItem and give it a custom font. My breakpoint hits the PCL code, but it never seems to venture into the OnAttached() override. I am wondering if there is something that I am missing. Do I have the ability to effect the actual styling on Navigation ToolbarItems?

iOS Effect Code

[assembly:ResolutionGroupName ("Core")] 
[assembly:ExportEffect (typeof(ToolbarItemEffect), "ToolbarItemEffect")] 
namespace Core.iOS.Effects 
{ 
    public class ToolbarItemEffect : PlatformEffect 
    { 
        protected override void OnAttached() 
        {
            var style = new UIStringAttributes 
            { 
                Font = UIFont.FromName("FontName", 24)
            }; 

            var navigationBar = (UINavigationBar) Control; 
            navigationBar.TitleTextAttributes = style; 
        } 

        protected override void OnDetached() 
        { 
        } 
    } 
}

Shared Code

    public class ToolbarItemEffect : RoutingEffect 
    { 
        public ToolbarItemEffect() : base("Core.ToolbarItemEffect") 
        { 
        } 
    }

Xaml on Navigation Page

<ContentPage.ToolbarItems>
    <ToolbarItem Text="Text" Command="{Binding TextCommand}">
        <ToolbarItem.Effects>
            <core:ToolbarItemEffect />
        </ToolbarItem.Effects>
    </ToolbarItem>--> 
</ContentPage.ToolbarItems>