WPF - TextBlocks in ListView not horizontally aligned

I created a ListView in a WPF Application with different TextBlocks. Each line can contain multiple text blocks, but when the line contains more than one text block, the first one matches the line, but the following text blocks are not horizontally aligned (see figure). I don't know what could be causing this, so I hope someone can provide some clarification.

Below is the XAML code.

<ListView ItemsSource="{Binding DataContext.Mechanics, RelativeSource={RelativeSource AncestorType={x:Type Window}}, UpdateSourceTrigger=PropertyChanged}" Height="auto" Width="1330" 
             Grid.Row="2" Grid.ColumnSpan="13" BorderThickness="0" Background="#FFF2F2F2">
        <ListView.ItemTemplate>
            <DataTemplate>
                <Grid>
                    <Grid.RowDefinitions>
                        <RowDefinition Height="18"/>
                    </Grid.RowDefinitions>
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition Width="22"/>
                        <ColumnDefinition Width="100"/>
                        <ColumnDefinition Width="1200"/>
                    </Grid.ColumnDefinitions>
                    <Label Content="{Binding MecID}" Grid.Column="0" Padding="0" FontSize="11" Background="#FFF2F2F2"/>
                    <Label Content="{Binding Name}" Grid.Column="1" Padding="0" FontSize="11" Margin="2, 0, 0, 0"/>
                    <ListView ItemsSource="{Binding MecJobs, UpdateSourceTrigger=PropertyChanged}" BorderThickness="0" Padding="-1" Height="18" Width="1200" Grid.Column="2" ScrollViewer.HorizontalScrollBarVisibility="Disabled" 
                             ScrollViewer.VerticalScrollBarVisibility="Disabled" Background="White">
                        <ListView.ItemContainerStyle>
                            <Style TargetType="ListBoxItem">
                                <Setter Property="Padding" Value="0"/>
                            </Style>
                        </ListView.ItemContainerStyle>
                        <ItemsControl.ItemTemplate>
                            <DataTemplate>
                                <Canvas>
                                    <ListViewItem Width="{Binding EstimatedTimeWidth}" Canvas.Left="{Binding Margin}" Background="{Binding Color}" Height="18" 
                                               Padding="0" Margin="0" ScrollViewer.VerticalScrollBarVisibility="Disabled">
                                        <TextBlock TextAlignment="Center" Height="18" Padding="0" Margin="0">
                                            <TextBlock.Text>
                                                <MultiBinding StringFormat="{}{0} - {1}">
                                                    <Binding Path="RegNumber" />
                                                    <Binding Path="CustomerName" />
                                                </MultiBinding>
                                            </TextBlock.Text>
                                        </TextBlock>
                                    </ListViewItem>
                                </Canvas>
                            </DataTemplate>
                        </ItemsControl.ItemTemplate>
                    </ListView>
                </Grid>
            </DataTemplate>
        </ListView.ItemTemplate>
        <ListView.ItemContainerStyle>
            <Style TargetType="ListBoxItem">
                <Setter Property="Padding" Value="0"/>
            </Style>
        </ListView.ItemContainerStyle>
    </ListView>
</Grid>

      

        
        
        
      

    

EDIT: The problem was resolved when the ListView was set to include a Stackpanel with Orientation = "Horizontal".