OxyPlot does not update view when adding Points (Dispatcher)

I'm working on a performance monitor showing plotting some x/y Points as AreaSeries. For presentation I'm updating my view several seconds and adding measuring points. Because of `InvalidOperationException`, I need to add the points inbetween a Dispatcher. I want to see the added points real-time - but the view does not update. There is no issue with the points or anything other, because adding all points before, I get my Plot.

.xaml file

    <UserControl x:Class="Gauge_3.PerformanceMonitor"
                 xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                 xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
                 xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
                 xmlns:local="clr-namespace:Gauge_3"
                 xmlns:oxy="http://oxyplot.org/wpf"
                 mc:Ignorable="d" 
                 d:DesignHeight="300" d:DesignWidth="300">
        <Grid>
            <Grid.RowDefinitions>
                <RowDefinition/>
                <RowDefinition />
                <RowDefinition />
            </Grid.RowDefinitions>
            <oxy:PlotView x:Name="fMonitor" Grid.Row="0" HorizontalContentAlignment="Stretch"/>
            <oxy:PlotView x:Name="sMonitor" Grid.Row="1"/>
            <oxy:PlotView x:Name="nMonitor" Grid.Row="2"/>
        </Grid>
    </UserControl>

.cs snippet, calling from another class

    public void PlotRealTime(double percent)
            {
                this.Dispatcher.Invoke(DispatcherPriority.Normal, new Action(() =>
                {
                    DataPoint dPoint = new DataPoint(new DateTime(2017, 01, 01, 14, internalCounter, 00).ToOADate(), percent);
                    sArea.Points.Add(dPoint);
                    if (internalCounter == 0)
                        sMonitor.Model.Series.Add(sArea);

                    sMonitor.Model.InvalidatePlot(true);
                }));

                internalCounter++;
            }