Crash on Xamarin.Android not being logged in Raygun

I have an Android app built using the Xamarin framework (Xamarin.Android 4.16.0 Business edition) and with the Raygun4Net component added from Xamarin's component repository. Following the instructions, I initialised the RaygunClient in my main activity's OnCreate method:

    string raygunApiKey = GetString(Resource.String.RaygunKey);
    RaygunClient.Attach(raygunApiKey);

Stepping through via debugging, our Raygun API key is correctly being loaded. However, there is a known bug that crashes the application completely when testing it on an Android 2.2 device (API level 8), returning immediately to the home screen. When I check our Raygun.io account, the error isn't listed.

The error is a Java.Lang.ClassNotFoundException, which is caused by attempting to reference the Android.Views.Animations.IInterpolator interface, which was introduced in API level 11, when instantiating LinearStepInterpolator. The stack trace is as follows:

0x21 in System.Diagnostics.Debugger.Mono_UnhandledException_internal
0x1 in System.Diagnostics.Debugger.Mono_UnhandledException
0x26 in object.8c3fa705-fd9a-4706-aSS6-d2c25044da4e
0x83 in Android.RuntimeJNIEnv.FindClass
0x1 in Android.RuntimeJNIEnv.CreateInstance
0x14 in Android.RuntimeJNIEnv.StartCreateInstance
0x2E in Java.Lang.Object..ctor
0x1 in [AppNamespace].Custom.LinearStepInterpolator..ctor
0xBD in [AppNamespace].WebFragment.OnActivityCreated
0x13 in Android.Support.V4.App.Fragment.n_OnActivityCreated_Landroid_os_Bundle_
0x17 in object.8c3fa705-fd9a-4706-a556-d2c25D44da4e

I also get the following in the ADB log:

 UNHANDLED EXCEPTION:
 Java.Lang.ClassNotFoundException: Exception of type 'Java.Lang.ClassNotFoundException' was thrown.
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x00000] in 

Do I need to override into some Android method that handles unhandled exceptions and manually invoke the RaygunClient to log this error? Or is this something that Raygun should be able to handle out-of-the-box? How can I get these 'unhandled' errors sent to Raygun.io?

Many thanks.