C# WPF DataGrid Header Style Not Updating after On Click event handling

I have a C# WPF project using a DataGrid to display a DataTable. The DataTable was populated by reading in a CSV file (unknown number of headers) and populating it using the CSVHelper nuget package.

using (FileStream? stream = fileInfo.OpenRead())
{ 
    using (StreamReader? reader = new(stream))
    using (CsvReader? csv = new(reader, csvConfiguration))
    {
        using CsvDataReader? dr = new(csv);
        dataTable.Load(dr);
    }
}

I am displaying this DataTable using the following XAML setup.

<DataGrid x:Name="DataGrid"
            ItemsSource="{Binding Data, UpdateSourceTrigger=PropertyChanged}"
            HorizontalScrollBarVisibility="Visible" 
            VerticalScrollBarVisibility="Visible"
            AlternatingRowBackground="AliceBlue"
            AlternationCount="2"
            CanUserSortColumns="False"
            AutoGeneratingColumn="Data_AutoGeneratingColumn"
            IsReadOnly="True"
            CanUserReorderColumns="False"
            Loaded="Data_Loaded"
          >

    <DataGrid.ColumnHeaderStyle>
        <Style BasedOn="{StaticResource {x:Type DataGridColumnHeader}}" TargetType="DataGridColumnHeader">
            <EventSetter Event="Click" Handler="DataGridColumnHeader_Click"/>
        </Style>
    </DataGrid.ColumnHeaderStyle>
</DataGrid>

I have added code to the Loaded Event for the DataGrid that cycles through all the DataGridColumn entries from DataGrid.Columns and will set their HeaderStyle depending on if they exist in a List<string> to either:

1. SelectedHeaderStyle
2. UnSelectedHeaderStyle

foreach (DataGridColumn column in grid.Columns)
{
    string headerText = column.Header.ToString();
    if (cSVConfigureContext.SelectedColumns.Contains(headerText))
    {
        column.HeaderStyle = selectedHeaderStyle;
    }
    else
    {
        column.HeaderStyle = notSelectedHeaderStyle;
    }
}

I am also handling the Click event for TargetType DataGridColumnHeader which will toggle the HeaderStyle between 1 and 2.

private void DataGridColumnHeader_Click(object sender, RoutedEventArgs e)
{
    var columnHeader = sender as DataGridColumnHeader;
    if (columnHeader != null)
    {
        string headerText = columnHeader.Content.ToString();
        if (cSVConfigureContext.SelectedColumns.Contains(headerText))
        {
           columnHeader.Style = notSelectedHeaderStyle;

           cSVConfigureContext.SelectedColumns.Remove(headerText);
        }
        else
        {
            columnHeader.Style = selectedHeaderStyle;
            cSVConfigureContext.SelectedColumns.Add(headerText);
        }
    }
    e.Handled = true;
}

This part all seems to work. However, adding a "Reset Headers" button to return to a default set of selected columns, is where things are not working.

If I load the window with the DataGrid and press the Reset button (which runs the same code used in the Loaded event, it works fine. But if I first click on any header to switch its state, the style on the column header does not change. I see the change in the SelectedColumns list of strings but no visual update in the DataGrid until I close that window and re-open a new DataGrid. But I can still click headers to change their state.

I've spent a couple hours googling options for forcing a redraw of the column headers but so far no luck.

Any ideas why the Reset button doesn't work after a Click event?