We've noticed a crash come through our telemetry channels that looks to be entirely within the esri stack (below). We enable the location dot by just setting MapView.LocationDisplay.IsEnabled to true. Any direction would be helpful. Though, perhaps this is just good info for the Runtime team for a possible fix.
SIGABRT: Invalid argument: location data source has been started.
ArcGISException.HandleCoreError (RuntimeCoreNet.GeneratedWrappers.CoreError error, System.Boolean throwException) C:\daily_r\api_xam\dotnet\api\src\Esri.ArcGISRuntime\Esri.ArcGISRuntime.Shared\ArcGISExceptions.cs:75
Interop.CheckError (System.IntPtr errorHandle, System.Boolean throwOnFailure, System.Runtime.InteropServices.GCHandle wrapperHandle) C:\daily_r\api_xam\dotnet\api_generated_interop\managed_wrappers\Interop.cs:104
CoreLocationDataSource.HandleStart (RuntimeCoreNet.GeneratedWrappers.CoreClientReference userDefinedError) C:\daily_r\api_xam\dotnet\api_generated_interop\managed_wrappers\CoreLocationDataSource.cs:470
LocationDataSource+<RuntimeCoreNet-GeneratedWrappers-ICoreCallback_LocationDataSource_StartCallback-StartCallback>d__19.MoveNext () C:\daily_r\api_xam\dotnet\api\src\Esri.ArcGISRuntime\Esri.ArcGISRuntime.Shared\Location\LocationDataSource.cs:172
AsyncMethodBuilderCore+<>c.<ThrowAsync>b__6_0 (System.Object state) /Library/Frameworks/Xamarin.iOS.framework/Versions/12.2.1.12/src/Xamarin.iOS/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/AsyncMethodBuilder.cs:1023
NSAsyncSynchronizationContextDispatcher.Apply () /Library/Frameworks/Xamarin.iOS.framework/Versions/12.2.1.12/src/Xamarin.iOS/Foundation/NSAction.cs:178
(wrapper managed-to-native) UIKit.UIApplication.UIApplicationMain(int,string[],intptr,intptr)
UIApplication.Main (System.String[] args, System.IntPtr principal, System.IntPtr delegate) /Library/Frameworks/Xamarin.iOS.framework/Versions/12.2.1.12/src/Xamarin.iOS/UIKit/UIApplication.cs:79
UIApplication.Main (System.String[] args, System.String principalClassName, System.String delegateClassName) /Library/Frameworks/Xamarin.iOS.framework/Versions/12.2.1.12/src/Xamarin.iOS/UIKit/UIApplication.cs:63
Application.Main (System.String[] args) /.../Main.cs:9