Параметр преобразователя "values" равен нулю, если конвертер используется после прокрутки DataGrid

Question

У меня есть DataGrid и несколько флажков, которые действуют как фильтры для видимости определенных строк в DataGrid. Это работает отлично, пока DataGrid не прокручивается; если вы попытаетесь отфильтровать DataGrid, установив один из флажков, преобразователь, который обрабатывает логику фильтрации, выдаст исключение, так как параметр значений в преобразователе теперь равен нулю.

Я не понимаю, почему это сначала работает, а потом ломается. Ниже представлен xaml и пример конвертера.

ПРЕОБРАЗОВАТЕЛЬ

        public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
    {
        //var softwareModel = (SoftwareModel)values[0];
        //var checkBox = (CheckBox)values[1];

        SoftwareModel softwareModel = values[0] as SoftwareModel;
        CheckBox checkBox = values[1] as CheckBox;

        if (checkBox.IsChecked == true)
        {
            foreach (var missingSoftwareItem in SharedClass.requiredSoftwareMissingOC) // for each missing software
            {
                if (SharedClass.SoftwareModelComparitor(softwareModel, missingSoftwareItem)) // if missing == total
                {
                    return Visibility.Collapsed;
                }
            }
        }

        return Visibility.Visible;
    }

XAML

<UserControl x:Class="NIThirdPartySoftwareChecker.Views.SoftwareChecksView"
         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:NIThirdPartySoftwareChecker.ViewModels"
         mc:Ignorable="d" 
         d:DesignHeight="450" d:DesignWidth="800">

<UserControl.Resources>
    <local:SoftwareListContainsToDataGridRowStyleConverter x:Key="SoftwareListContainsToDataGridRowStyleConverter"/>
    <local:RequiredInstalledSoftwareToVisibiltyConverter x:Key="RequiredInstalledSoftwareToVisibiltyConverter"/>
    <local:RequiredMissingSoftwareToVisibiltyConverter x:Key="RequiredMissingSoftwareToVisibiltyConverter"/>
    <local:UnrequiredSoftwareToVisibiltyConverter x:Key="UnrequiredSoftwareToVisibiltyConverter"/>

    <Style x:Key="DataGridRowStyle" 
           TargetType="{x:Type DataGridRow}">
        <Setter Property="Background" 
                Value="{Binding RelativeSource={RelativeSource Self}, Converter={StaticResource SoftwareListContainsToDataGridRowStyleConverter}}"/>
        <Style.Triggers>
            <DataTrigger Binding="{Binding ElementName=chbx_hideUnrequiredSoftware, Path=IsChecked}" Value="True">
                <Setter Property="Visibility">
                    <Setter.Value>
                        <MultiBinding Converter="{StaticResource UnrequiredSoftwareToVisibiltyConverter}">
                            <Binding Path="."/>
                            <Binding ElementName="chbx_hideUnrequiredSoftware"/>
                        </MultiBinding>
                    </Setter.Value>
                </Setter>
            </DataTrigger>

            <DataTrigger Binding="{Binding ElementName=chbx_hideRequiredInstalledSoftware, Path=IsChecked}" Value="True">
                <Setter Property="Visibility">
                    <Setter.Value>
                        <MultiBinding Converter="{StaticResource RequiredInstalledSoftwareToVisibiltyConverter}">
                            <Binding Path="."/>
                            <Binding ElementName="chbx_hideRequiredInstalledSoftware"/>
                        </MultiBinding>
                    </Setter.Value>
                </Setter>
            </DataTrigger>

            <DataTrigger Binding="{Binding ElementName=chbx_hideRequiredMissingSoftware, Path=IsChecked}" Value="True">
                <Setter Property="Visibility">
                    <Setter.Value>
                        <MultiBinding Converter="{StaticResource RequiredMissingSoftwareToVisibiltyConverter}">
                            <Binding Path="."/>
                            <Binding ElementName="chbx_hideRequiredMissingSoftware"/>
                        </MultiBinding>
                    </Setter.Value>
                </Setter>
            </DataTrigger>
        </Style.Triggers>
    </Style>

    <CollectionViewSource x:Key="totalSoftwareCollectionViewSource" 
                          Source="{Binding TotalSoftwareOC}" 
                          CollectionViewType="ListCollectionView"/>

</UserControl.Resources>

<Grid>
    <Border Style="{StaticResource UI.BorderInnerStyle}">
        <Grid>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="auto"/>
                <ColumnDefinition Width="*"/>
            </Grid.ColumnDefinitions>
            <Grid.RowDefinitions>
                <RowDefinition Height="auto"/>
                <RowDefinition Height="*"/>
            </Grid.RowDefinitions>

            <StackPanel Grid.Row="1"
                        Margin="5">

                <Label Content="Filters"
                       Margin="5"
                       FontWeight="Bold"
                       HorizontalAlignment="Center"/>

                <CheckBox x:Name="chbx_hideUnrequiredSoftware" 
                          Content="Hide unrequired software" 
                          Foreground="White"
                          IsChecked="{Binding UnrequiredSoftwareIsChecked}"/>

                <CheckBox x:Name="chbx_hideRequiredInstalledSoftware" 
                          Content="Hide required installed software" 
                          Foreground="Green"
                          IsChecked="{Binding RequiredInstalledSoftwareIsChecked}"/>

                <CheckBox x:Name="chbx_hideRequiredMissingSoftware" 
                          Content="Hide required missing software" 
                          Foreground="Red"
                          IsChecked="{Binding RequiredMissingSoftwareIsChecked}"/>
            </StackPanel>

            <Label Grid.Row="0" 
                   Grid.Column="1"
                   Margin="5"
                   Content="Total software" 
                   FontWeight="Bold"
                   HorizontalAlignment="Center"/>

            <DataGrid Grid.Row="1" 
                      Grid.Column="1"
                      Margin="5"
                      RowStyle="{StaticResource DataGridRowStyle}" 
                      VirtualizingStackPanel.VirtualizationMode="Standard"
                      RowHeight="20"
                      MinRowHeight="0"
                      IsReadOnly="True"
                      HeadersVisibility="Column"
                      ItemsSource="{Binding Source={StaticResource totalSoftwareCollectionViewSource}}"
                      AutoGenerateColumns="False"
                      SelectionMode="Single"
                      SelectionUnit="FullRow"
                      SelectedItem="{Binding SoftwareSelectedRow}">

                <DataGrid.InputBindings>
                    <MouseBinding MouseAction="LeftDoubleClick"
                                  Command="{Binding DataGridRowDoubleClickCommand}" />
                </DataGrid.InputBindings>

                <DataGrid.Columns>
                    <DataGridTextColumn Binding="{Binding Name}" 
                                        Header="Name"/>
                    <DataGridTextColumn Binding="{Binding Version}" 
                                        Header="Version"/>
                </DataGrid.Columns>
            </DataGrid>
        </Grid>
    </Border>
</Grid>