ReactiveUI in Xamarin Forms 1.3.1 Unified API Crashing on Device only

Xamarin folk can you please please have a look at this.

This worked perfectly in 1.3.0 non unified API. After updating to Xamarin Unified API it works fine in the iOS Simulator, however deploying to an iPhone it always crashes in AppDelegate on RxApp.SuspensionHost.SetupDefaultSuspendResume();

I tried everything to no avail. Any ideas? I believe this must be a Xamarin bug? 1.3.0 non unified worked a treat.

The error is below:

System.ExecutionEngineException: Attempting to JIT compile method 'System.Reactive.Linq.QueryLanguage:Switch (System.IObservable1<System.IObservable1>)' while running with --aot-only. See http://docs.xamarin.com/ios/about/limitations for more information.

I have full testable source code up on GitHub.
https://github.com/michaeldimoudis/RxFormsTest

Thank you.