title: WPF ListView.GroupStyle not displaying group header
body: <p>I have the following xaml:</p>
  
  <pre><code>&lt;ListView Name="lstCurrentAccounts"&gt;
      &lt;ListView.View&gt;
          &lt;GridView x:Name="grvCurrentAccounts" AllowsColumnReorder="True"&gt;
              &lt;GridViewColumn DisplayMemberBinding="{Binding AccountName}" Width="Auto" Header="Account Name" /&gt;
              &lt;GridViewColumn DisplayMemberBinding="{Binding ReconciledBalance}" Width="Auto" Header="Reconciled" /&gt;
              &lt;GridViewColumn DisplayMemberBinding="{Binding Balance}" Width="Auto" Header="Balance" /&gt;
          &lt;/GridView&gt;
      &lt;/ListView.View&gt;
      &lt;ListView.GroupStyle&gt;
          &lt;GroupStyle&gt;
              &lt;GroupStyle.HeaderTemplate&gt;
                  &lt;DataTemplate&gt;
                      &lt;TextBlock Text="{Binding Name}" /&gt;
                  &lt;/DataTemplate&gt;
              &lt;/GroupStyle.HeaderTemplate&gt;
          &lt;/GroupStyle&gt;
      &lt;/ListView.GroupStyle&gt;
  &lt;/ListView&gt;
  </code></pre>
  
  <p>And the following code-behind:</p>
  
  <pre><code>private void updateData()
  {
      MyContext dc = new MyContext();
      var c = (from x in dc.Accounts select x).ToList();
      lstCurrentAccounts.ItemsSource = c;
  
      CollectionView view = (CollectionView)CollectionViewSource.GetDefaultView(lstCurrentAccounts.ItemsSource);
      PropertyGroupDescription groupDescription = new PropertyGroupDescription("AccountTypeName");
  
      view.GroupDescriptions.Add(groupDescription);
  
      var r = (from x in dc.RepeatingTransactions where x.Deleted == false orderby x.NextOccurence select x).Take(10).ToList();
      lstRepeating.ItemsSource = r;
  
  }
  </code></pre>
  
  <p>Now this should display a ListView with the data grouped by "AccountTypeName", which is a string property of each Account element. When I run the application the data is grouped properly, however the group Header, as defined in the GroupStyle.HeaderTemplate is blank, as opposed to displaying the appropriate AccountTypeName.</p>
  
  <p>What am I doing wrong?</p>