Images not showing in XF OSX project

The following is an extract from the XAML or a view whichworks successfully on UWP, Android and iOs platforms:

<Image x:Name="Logo" Style="{StaticResource LogoStyle}">
    <Image.Source>
       <OnPlatform x:TypeArguments="ImageSource">
        <On Platform="Android" Value="logo_splash" />
        <On Platform="UWP" Value="Assets/logo_splash.png" />
        <On Platform="macOS" Value="logo_splash"/>
       </OnPlatform>
    </Image.Source>
    <Image.HeightRequest>
        <OnIdiom x:TypeArguments="x:Double" Desktop="100" Phone="95"/>
    </Image.HeightRequest>
    <Image.VerticalOptions>
        <OnIdiom x:TypeArguments="LayoutOptions" Desktop="End" Phone="Start"/>
    </Image.VerticalOptions>
</Image>

As you can see I've added an On Platform selector for the macOS platform.

While the image appears as expected on other platforms it is not seen on the Mac.

In my OSX project I've added the image to the resources folder and set the build action to 'BundleResource'.

I'm using package Xamarin.Forms 2.5.0.122203.

I can't help thinking I've missed something obvious, can anyone please suggest what I'm doing wrong.

Thanks in advance
Dave