In one of my charts I have defined one ScatterSeries bound to an observable collection of data points in my view model

<ig:XamDataChart x:Name="scatterChart" Visibility="Visible" Margin="10" Title="{Binding ChartLabel}"
MinHeight="400" MinWidth="400" Grid.Row="1" Grid.ColumnSpan="2" Grid.RowSpan="3"
HorizontalZoomable="False" VerticalZoomable="False">
<ig:XamDataChart.Axes>
<ig:NumericXAxis x:Name="scatterXAxis" Title="{Binding Captions[LENGTHCAPTION]}" MinimumValue="0" MaximumValue="{Binding MaxXValue}">
<ig:NumericXAxis.LabelSettings>
<ig:AxisLabelSettings Location="OutsideBottom" Extent="50" FontSize="10" Visibility="Visible" />
</ig:NumericXAxis.LabelSettings>
</ig:NumericXAxis>
<ig:NumericYAxis x:Name="scatterYAxis" Title="{Binding Captions[DURATIONCAPTION]}" MinimumValue="0" MaximumValue="{Binding MaxYValue}">
<ig:NumericYAxis.LabelSettings>
<ig:AxisLabelSettings Location="OutsideLeft" Extent="50" FontSize="10" Visibility="Visible" />
</ig:NumericYAxis.LabelSettings>
</ig:NumericYAxis>
</ig:XamDataChart.Axes>
<ig:XamDataChart.Series>
<ig:ScatterSeries Name="scatter" ItemsSource="{Binding ScatterChartValues}" Visibility="Visible"
MarkerType="Automatic" MarkerBrush="Green"
XMemberPath="X" YMemberPath="Y"
YAxis="{Binding ElementName=scatterYAxis}"
XAxis="{Binding ElementName=scatterXAxis}"
ShowDefaultTooltip="True">
</ig:ScatterSeries>
</ig:XamDataChart.Series>
</ig:XamDataChart>

The collection of data points is refreshed after user interaction.  Change notifications are submitted.

Chart title and axis labels are refreshed as well as axis labels but data points are not positioned where I expect them to be in the plot area.  I only see one data point in zero zero position, but tooltip tell me that it actually should have been positioned elsewhere.

Please tell me how I can force plot area refresh.