PushModalAsync() - Android L (5)

Hi,

I've noticed one of our apps has stopped working for devices that have updated to Android 5 (Lollipop).

I've narrowed it down to the Navigation.PushModalAsync() calls. The exception/Stack Trace I'm seeing is..

No known package when getting value for resource number 0xff303030

11-20 10:44:20.730 I/MonoDroid( 2962): UNHANDLED EXCEPTION:
11-20 10:44:20.769 I/MonoDroid( 2962): Android.Content.Res.Resources+NotFoundException: Exception of type 'Android.Content.Res.Resources+NotFoundException' was thrown.
11-20 10:44:20.769 I/MonoDroid( 2962):   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x00000] in <filename unknown>:0 
11-20 10:44:20.769 I/MonoDroid( 2962):   at Android.Runtime.JNIEnv.CallNonvirtualVoidMethod (IntPtr jobject, IntPtr jclass, IntPtr jmethod, Android.Runtime.JValue[] parms) [0x00084] in /Users/builder/data/lanes/monodroid-mlion-monodroid-4.18-series/5474129a/source/monodroid/src/Mono.Android/src/Runtime/JNIEnv.g.cs:896 
11-20 10:44:20.769 I/MonoDroid( 2962):   at Android.Views.View.SetBackgroundResource (Int32 resid) [0x00070] in /Users/builder/data/lanes/monodroid-mlion-monodroid-4.18-series/5474129a/source/monodroid/src/Mono.Android/platforms/android-19/src/generated/Android.Views.View.cs:14992 
11-20 10:44:20.769 I/MonoDroid( 2962):   at Xamarin.Forms.Platform.Android.Platform.PresentModal (Xamarin.Forms.Page modal) [0x00000] in <filename unknown>:0 
11-20 10:44:20.769 I/MonoDroid( 2962):   at Xamarin.Forms.Platform.Android.Platform+<PushModalAsync>d__e.MoveNext () [0x00000] in <filename unknown>:0

I've updated the nuget packages and the Android sdk tools, not sure what else to try.

It happens for all modal navigation, but NOT non modal, i.e. Navigation.PushAsync() works as expected.

Thanks.