I have an issue with Notification Service Extension. I have followed step by step documentation https://developer.xamarin.com/guides/ios/platform_features/introduction-to-ios10
If anyone else comes here, the code by original poster works for me and the bug mention is now marked as fixed. If I have one tip, do not try to do this on Windows. You will be in for a whole world of pain and will get nowhere (actually, it did work for me, once!). Also expect Visual Studio on Mac to crash, a lot, if you try to debug!