The issue occurs when new Telerik project is created (or create Xamarin.Form new project, add the Telerik UI for Xamarin assemblies manually and then add some of the Telerik UI for Xamarin Item Templates.

All platform projects are including assemblies from the Portable. For example for the Android project assemblies should be included from the Android folder. 

Also this issue affects the simple login template - for example the entry controls for user name and password are not visible.
UWP it complains that the common.dll is missing even though that reference is present. I manually removed and added it to see if it resolves the issue with no luck.

Workaround:

add the Telerik UI for Xamarin suite using the Telerik UI for Xamarin Nuget Server.