Setting Property in a PropertyGrid Style through Data Binding

I am trying to force a datagrid property of type collection (ItemContainer) and referenced in the associated ViewModel to Auto expand in a PropertyGrid by using a databinding from a custom IsExpandable property defined in a Model ItemContainer.

I have tried to Set the property IsExpanded in XAML from ItemContainer.IsExpanded as follow:

View

<propgrid:PropertyGrid x:Name="StrategyGrid" Grid.Column="0" 
	SelectedObject="{Binding GridItems}"
	CollectionDisplayMode="Expandable" 
	PropertyExpandability="ForceSimple">
 
<propgrid:PropertyGrid.Resources>
	<Style x:Key="{x:Type primitives:PropertyGridDataAccessorItem}"
		TargetType="{x:Type primitives:PropertyGridDataAccessorItem}">
		 
		<Style.Triggers>    
				<DataTrigger Binding="{Binding DataAccessorType, RelativeSource={RelativeSource Self}}" Value="Property">
                            
				<Setter Property="IsExpanded" Value="{Binding IsExpanded, Mode=TwoWay}" />
                     </DataTrigger>
		</Style.Triggers>
	</Style>
</propgrid:PropertyGrid.Resources>

ViewModel

public class StrategyGridViewModel : DataGridViewModelBase
{
	Public GridItems GridItems { get; set; }
	
	GridItems = new GridItems();
	GridItems.Parameters = new ItemContainer();
	GridItems.Parameters.Add("Parameter1", 1);
	GridItems.Parameters.Add("Parameter2", 2);
	
	GridItems.Parameters.IsExpanded = true;
}

Model GridItems

public class StrategyGridItems
{
        [Category("Category")]
        [Description("This is a description")]
        public ItemContainer Parameters { get; set; }
}

Model ItemContainer

public class ItemContainer : Dictionary<string, object>
{
	public bool IsExpanded { get; set; }
}

I believe the XAML <Style > is correct except for the DataBinding to ItemContainer.IsExpanded; any idea what I am doing wrong here?