Switching Target Framework to Xamarin.Mac Full .NET Framework >= 4.6.1 makes Xamarin.Forms.Platform.MacOS disappear

Question

I need to use Xamarin.Mac Full for a nuget i need to use. But when i switch to it Xamarin.Forms.Platform.MacOS disappears with the message: The type or namespace name 'MacOS' does not exist in the namespace 'Xamarin.Forms.Platform' (are you missing an assembly reference? I've tried all .NET Framework versions higher than and equal to 4.6.1 and none have made any difference.

Is this a bug, is there some way to fix this?