Did you know you can report issues with Visual Studio 2017 or Visual Studio for Mac directly within the IDE? Just use Help > Report a Problem to file your issue.
Attachment 16253 Details for
Bug 41665[Cycle 7, VS 2013 only] "'System.ComponentModel.INotifyPropertyChanged' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.ObjectModel" for Android projects that reference PCLs that use `INotifyPropertyChanged`