Commented Issue: CheckedListBox SelectedItems binding not work in datatemplate [18431]

When I create checkedListBox directly (without datatemplate) SelectedItems binding works great. But if I create CheckedListBox in datatemplate like this
 
<ContentControl Content="{Binding}" Grid.Column="1">
<ContentControl.ContentTemplate>
<DataTemplate>
<xctk:CheckListBox
ItemsSource="{Binding TestItems}"
SelectedItems="{Binding CheckedItems}"/>
</DataTemplate>
</ContentControl.ContentTemplate>
</ContentControl>
 
SelectedItems binding totaly fails
Comments: ** Comment from web user: thelehehmanlip **

I've seen many posts saying this is fixed in later versions, but i'm having the same issue in v2.1. Is this still a bug? What's the workaround? Why does this keep getting broken?