ExportToFile failed when the chart has modifier that inherited from VerticalSliceModifier

Hi,
We inherited from VerticalSliceModifier and then add a VerticalLineAnnotation, but the ExportToFile failed.What is the reason for this, and how can one correctly inherit from VerticalSliceModifier? The code below can simply reproduce this error. My debugging results show that OnAnnotationCollectionChanged is executed when generating the image, and there are 2 Annotations in the sender.

public class TestModfiy: VerticalSliceModifier
{
public override void OnAttached()
{
base.OnAttached();
}

protected override void OnAnnotationCollectionChanged(object sender, NotifyCollectionChangedEventArgs args)
{
base.OnAnnotationCollectionChanged(sender, args);
}

public override void OnDetached()
{
base.OnDetached();
}
}

The Exception:

ArgumentOutOfRangeException: 索引超出范围。必须为非负值并小于集合大小。

参数名: index

Stack Trace:
在 System.ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument argument, ExceptionResource resource)
在 System.Collections.Generic.List1.get_Item(Int32 index)
在 SciChart.Charting.Visuals.SciChartSurface.CreateCloneOfSurfaceInMemory(Size newSize)
在 SciChart.Charting.Visuals.SciChartSurfaceBase.mro(ExportType arb, Boolean arc, Nullable1 ard)
在 SciChart.Charting.Visuals.SciChartSurfaceBase.ExportToFileInternal(String fileName, ExportType exportType, Boolean useXamlRenderSurface, Nullable1 size)
在 SciChart.Charting.Visuals.SciChartSurfaceBase.ExportToFile(String fileName, ExportType exportType, Boolean useXamlRenderSurface)
在 SciChart.Examples.ExternalDependencies.Controls.Toolbar2D.CustomModifiers.CustomExportModifier.Export(String filter, Boolean useXaml, Nullable1 size)
在 SciChart.Examples.ExternalDependencies.Controls.Toolbar2D.CustomModifiers.CustomExportModifier.<.ctor>b__16_2()
在 MS.Internal.Commands.CommandHelpers.CriticalExecuteCommandSource(ICommandSource commandSource, Boolean userInitiated)
在 System.Windows.Controls.Primitives.ButtonBase.OnClick()
在 System.Windows.Controls.Button.OnClick()
在 System.Windows.Controls.Primitives.ButtonBase.OnMouseLeftButtonUp(MouseButtonEventArgs e)
在 System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
在 System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
在 System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
在 System.Windows.UIElement.ReRaiseEventAs(DependencyObject sender, RoutedEventArgs args, RoutedEvent newEvent)
在 System.Windows.UIElement.OnMouseUpThunk(Object sender, MouseButtonEventArgs e)
在 System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
在 System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
在 System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
在 System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
在 System.Windows.UIElement.RaiseTrustedEvent(RoutedEventArgs args)
在 System.Windows.Input.InputManager.ProcessStagingArea()
在 System.Windows.Input.InputManager.ProcessInput(InputEventArgs input)
在 System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport)
在 System.Windows.Interop.HwndMouseInputProvider.ReportInput(IntPtr hwnd, InputMode mode, Int32 timestamp, RawMouseActions actions, Int32 x, Int32 y, Int32 wheel)
在 System.Windows.Interop.HwndMouseInputProvider.FilterMessage(IntPtr hwnd, WindowMessage msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
在 System.Windows.Interop.HwndSource.InputFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
在 MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
在 MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
在 System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
在 System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)