Collapsed Expander crashes my app

[MoHa173]

Hello Guys, I have Tried to put a DataGrid in to an Expender Object.

On the MADesign Style my App was crashed, with the Win Styled Expander the app is working here my Code:

Working Code:

<Expander Style="{DynamicResource MaterialDesignExpander}" Name="MyExpander" Margin="10,10" HorizontalAlignment="Stretch" BorderBrush="{DynamicResource MaterialDesignBody}">
                <Expander.Content>
                    <Grid>
                        <DataGrid Name="dataGrid1"
                              ScrollViewer.HorizontalScrollBarVisibility="Visible"
                              Cursor="Hand"
                              Grid.Row="1"
                              Grid.ColumnSpan="4"
                              MaxHeight="400" 
                              MaxWidth="2000"
                              Width="auto" 
                              Height="auto" 
                              VerticalAlignment="Top" 
                              EnableColumnVirtualization="True" 
                              EnableRowVirtualization="True" 
                              ItemsSource="{Binding ListOfHeaderData, IsAsync=True}" />
                    </Grid>
                </Expander.Content>
                	<Expander.Style>
                    <Style TargetType="Expander">
                        <Setter Property="IsExpanded" Value="False" />
                        <Setter Property="Header" Value="Click to See More" />
                        <Style.Triggers>
                            <DataTrigger Binding="{Binding IsExpanded,RelativeSource={RelativeSource Self} Value="True">
                                <Setter Property="Header" Value="Click to See Less" />
                            </DataTrigger>
                        </Style.Triggers>
                    </Style>
                </Expander.Style>
            </Expander>

And the Code where crash:

 <Expander Grid.Row="1" Grid.ColumnSpan="3" Style="{DynamicResource MaterialDesignExpander}" IsExpanded="True" Header="Baugruppen Auswahl:">
            <Grid MaxHeight="460">
                <DataGrid Name="dataGrid1"
                              ScrollViewer.HorizontalScrollBarVisibility="Visible"
                              Cursor="Hand"
                              Grid.Row="1"
                              Grid.ColumnSpan="4"
                              MaxHeight="400" 
                              MaxWidth="2000"
                              Width="auto" 
                              Height="400" 
                              VerticalAlignment="Top" 
                              EnableColumnVirtualization="True" 
                              EnableRowVirtualization="True" 
                              ItemsSource="{Binding ListOfHeaderData, IsAsync=True}" />
            </Grid>
        </Expander>
 

I think the renderer trys in collapsed mode to render all Data inside my datasource without restrictions. And fills my RAM with lots off Data.

I think the solve is in the Style section from the working code. But if I use this section the Expander has no MADesign.

I am an WPF beginner and need help to fix that :(

I hope someone can help me.

[ElieTaillard]

Can you provide a test repo please ? It would help us to solve the problem.