Xamarin.Forms.Platform.WP8 issue

After the latest upgrade, I get these errors in both WP8 and WP81 projects, in both App.xaml and MainPage.xaml - any ideas?

Error 24 Cannot resolve dependency to assembly 'Xamarin.Forms.Platform.WP8, Version=1.2.3.0, Culture=neutral, PublicKeyToken=null' because it has not been preloaded. When using the ReflectionOnly APIs, dependent assemblies must be pre-loaded or loaded on demand through the ReflectionOnlyAssemblyResolve event. C:\xsl-home\kleverlogic\FlashValet\Mobile\Customer\Customer.WinPhone81\App.xaml 1 1 KleverLogic.FlashValet.Customer.WinPhone81