VS 写的WPF程序，中间画线不显示了

各位我用VS 2019 写的WPF程序 ，绑定数据后，部分信息显示出现问题了（中间的横线没有了），求指导

代码如下：

<TextBlock Text="{Binding CurrentDevice.DeviceName}" Foreground="White" FontSize="14" Margin="0,15"/>
                <ItemsControl Grid.Row="1" ItemsSource="{Binding CurrentDevice.MonitorValueList}">

                    <ItemsControl.ItemTemplate>
                        <DataTemplate>
                            <Grid>
                                <Grid.ColumnDefinitions>
                                    <ColumnDefinition Width="60"/>
                                    <ColumnDefinition/>
                                    <ColumnDefinition Width="30"/>
                                    <ColumnDefinition Width="30"/>
                                Grid.ColumnDefinitions>
                                <TextBlock Text="{Binding ValueName,StringFormat=\{0\}:}" Foreground="#99FFFFFF" VerticalAlignment="Center"/>
                                <lvc:CartesianChart Grid.Column="1" MinHeight="30" DataTooltip="{x:Null}">
                                    <lvc:CartesianChart.Series>
                                        <lvc:LineSeries Fill="Transparent" Values="{Binding Values}" PointGeometrySize="0" StrokeThickness="0.5">
                                            <lvc:LineSeries.Stroke>
                                                <LinearGradientBrush EndPoint="1,0" StartPoint="0,0">
                                                    <GradientStop Color="Orange" Offset="0.5"/>
                                                    <GradientStop Color="#00FFFFFF" Offset="0"/>
                                                    <GradientStop Color="#FFFFE2AE" Offset="0.1"/>
                                                LinearGradientBrush>
                                            lvc:LineSeries.Stroke>
                                        lvc:LineSeries>
                                    lvc:CartesianChart.Series>
                                    <lvc:CartesianChart.AxisX>
                                        <lvc:Axis ShowLabels="False"/>
                                    lvc:CartesianChart.AxisX>
                                    <lvc:CartesianChart.AxisY>
                                        <lvc:Axis ShowLabels="False"/>
                                    lvc:CartesianChart.AxisY>
                                lvc:CartesianChart>
                                <TextBlock Text="{Binding CurrentValue}" Grid.Column="2" Foreground="#99FFFFFF" VerticalAlignment="Center" HorizontalAlignment="Right"/>
                                <TextBlock Text="{Binding Unit}" Grid.Column="3" Foreground="#99FFFFFF" VerticalAlignment="Center" HorizontalAlignment="Left" Margin="3,0,0,0"/>
                            Grid>
                        DataTemplate>
                    ItemsControl.ItemTemplate>