A datagrid bound to concurrentqueue is not getting updated as items get added

See more:

C#

WPF

DataGrid

I am developing a multi-threaded monitor application. In addition to the "main" thread, there are 2 sets of reader-writer threads connecting to 2 instances of a production application. Part of the message flow from the production apps are EvtMsg items. These are placed by the reader thread into a ConcurrentQueue for that particular side (LEFT or RIGHT). The main window has an EvtMsg button for each side. When you click on one of them, it will bring up a window that contains a DataGrid, populated from the given ConcurrentQueue.

The problem is when I open an EvtMsg window, the DataGrid is populated with all EvtMsg objects received up to that point (say, for example, 3 items), but upon receiving new EvtMsg messages, they don't update the window (I am using INotifyPropertyChanged, and I have debugged to verify that the ConcurrentQueue has the new items).

Data structures:

public enum eSide : int { LEFT = 0, RIGHT = 1 }
public const int C_numSides = 2;
// ....

public class EvtMsg : INotifyPropertyChanged
{
    public  ulong        sequenceNumber         { get; set; }
    public  string       description            { get; set; }
    // ....
}

public class AnEvtQueue : INotifyPropertyChanged
{
    public ConcurrentQueue<EvtMsg> EvtQueue { get; set; }

    public AnEvtQueue()
    {
        EvtQueue = new ConcurrentQueue<EvtMsg>();
    }
    // ....
}

public class EvtHandler : INotifyPropertyChanged
{
    public AnEvtQueue[]     Sides     {get; set;}

    public EvtHandler()
    {
        Sides = new AnEvtQueue[C_numSides];
        Sides[(int)eSide.LEFT ] = new AnEvtQueue();
        Sides[(int)eSide.RIGHT] = new AnEvtQueue();
    }
    // ....
    public void AddEvtMsg(eSide WhichSide, EvtMsg msg)
    {
        Sides[side].EvtQueue.Enqueue(msg);
    }
    // ....
}

xaml:

<DataGrid Grid.Row="2"
          AutoGenerateColumns="False"
          IsReadOnly="True"
          SelectionMode="Single"
          SelectionUnit="FullRow"
          GridLinesVisibility="None"
          Name="StatList"
          ItemsSource="{Binding NotifyOnSourceUpdated=True}">
    <DataGrid.Columns>
        <!-- Col 0: Sequence # -->
        <DataGridTextColumn Binding="{Binding Path=sequenceNumber}"
                        ElementStyle="{StaticResource DGCell_RightAlignStyle}"
                        Header="Sequence #" />

        <!-- Col 0: EvtMsg Text -->
        <DataGridTextColumn Binding="{Binding Path=description}"
                            FontFamily="Courier New"
                            Header="EvtMsg Text" />
    </DataGrid.Columns>
</DataGrid>

<!--     ....     -->

Code-behind:

    public EvtMsgWindow(eSide WhichSide)
    {
        public ApplicationViewModel AppVM = ApplicationViewModel.Instance;
        InitializeComponent();

        StatList.ItemsSource = AppVM.TheEvtHandler.Sides[(int)WhichSide].EvtQueue;
    }
}

What I have tried:

I had tried an ObservableCollection, but this didn't seem to work with multiple threads (socket thread adds, GUI thread reads).