I am signing both pcl and uwp and getting error:
System.IO.FileLoadException: Could not load file or assembly 'Xamarin.Forms.Xaml, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. A strongly-named assembly is required. (Exception from HRESULT: 0x80131044)
Indeed the assembly Xamarin.Forms.Xaml is not signed (Strong name = false)