IsOpen forced to be false when using nested Dock Sites using MVVM

<UserControl
    x:Class="xxx"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:behaviors="http://schemas.microsoft.com/xaml/behaviors"
    xmlns:controls="xxx"
    xmlns:docking="http://schemas.actiprosoftware.com/winfx/xaml/docking"
    xmlns:viewModels="xxx">
    <UserControl.Resources>
        <Style
            x:Key="DockSiteStyle"
            BasedOn="{StaticResource {x:Type docking:DockSite}}"
            TargetType="{x:Type controls:CustomDockSite}">
            <Setter Property="AreNewTabsInsertedBeforeExistingTabs" Value="False" />
            <Setter Property="CanDocumentWindowsFloat" Value="False" />
            <Setter Property="CanToolWindowsAttach" Value="True" />
            <Setter Property="CanToolWindowsAutoHide" Value="False" />
            <Setter Property="CanToolWindowsBecomeDocuments" Value="False" />
            <Setter Property="CanToolWindowsFloat" Value="False" />
            <Setter Property="IsLiveSplittingEnabled" Value="False" />
            <Setter Property="Padding" Value="0" />
        </Style>

        <Style x:Key="DockingWindowStyle" TargetType="{x:Type docking:DockingWindow}">
            <Setter Property="IsActive" Value="{Binding Path=IsActive, Mode=TwoWay}" />
            <Setter Property="IsOpen" Value="{Binding Path=IsOpen, Mode=TwoWay}" />
            <Setter Property="SerializationId" Value="{Binding Path=ID, Mode=OneWay}" />
            <Setter Property="Title" Value="{Binding Path=FullName, Mode=TwoWay}" />
        </Style>

        <Style
            x:Key="SlotWindowStyle"
            BasedOn="{StaticResource DockingWindowStyle}"
            TargetType="{x:Type controls:SlotWindow}">
            <Setter Property="HasOptionsButton" Value="False" />
            <Setter Property="HasTitleBar" Value="False" />
            <Setter Property="UseAutoHideTitleBar" Value="True" />
        </Style>

        <Style
            x:Key="SlotGroupWindowStyle"
            BasedOn="{StaticResource DockingWindowStyle}"
            TargetType="{x:Type docking:DocumentWindow}" />

        <controls:SlotViewModelTemplateSelector x:Key="SlotViewModelTemplateSelector" />

        <DataTemplate x:Key="SlotGroupTemplate" DataType="{x:Type viewModels:SlotGroupViewModel}">
            <controls:SlotGroupDockSite
                x:Name="DockSite"
                Layout="{Binding Layout}"
                Style="{StaticResource DockSiteStyle}"
                ToolItemContainerStyle="{StaticResource SlotWindowStyle}"
                ToolItemTemplateSelector="{StaticResource SlotViewModelTemplateSelector}"
                ToolItemsSource="{Binding Items}">
                <docking:SplitContainer>
                    <docking:SplitContainer>
                        <docking:ToolWindowContainer />
                    </docking:SplitContainer>
                </docking:SplitContainer>
            </controls:SlotGroupDockSite>
        </DataTemplate>
    </UserControl.Resources>
    <controls:MainDockSite
        x:Name="DockSite"
        DocumentItemContainerStyle="{StaticResource SlotGroupWindowStyle}"
        DocumentItemTemplate="{StaticResource SlotGroupTemplate}"
        DocumentItemsSource="{Binding Items}"
        Layout="{Binding Layout}"
        Style="{StaticResource DockSiteStyle}">
        <docking:SplitContainer>
            <docking:Workspace>
                <docking:TabbedMdiHost ContainersHaveNewTabButtons="True" />
            </docking:Workspace>
        </docking:SplitContainer>
    </controls:MainDockSite>
</UserControl>

I am attempting to implement nested dock sites using MVVM. However, when the DockSite defined in the SlotGroupTemplate is created, the IsOpen property bound to the ToolWindow becomes false. It has been observed that setting a value to the ToolItemContainerStyle property triggers code that destroys and recreates all DockingWindows.

Here is a step-by-step method to reproduce the issue:
1. Create a SlotGroup (Inner DockSite) and a Slot (ToolWindow).
2. Delete both of them.
3. Recreate SlotGroup and Slot.
4. Change the IsOpen property of the Slot, observed to be false.

<DataTemplate x:Key="SlotGroupTemplate" DataType="{x:Type viewModels:SlotGroupViewModel}">
    <controls:SlotGroupDockSite
        x:Name="DockSite"
        Layout="{Binding Layout}"
        Style="{StaticResource DockSiteStyle}"
        ToolItemContainerStyle="{StaticResource SlotWindowStyle}"
        ToolItemTemplateSelector="{StaticResource SlotViewModelTemplateSelector}">
        <!--  ToolItemsSource="{Binding Items}"  -->
        <behaviors:Interaction.Triggers>
            <behaviors:DataTrigger
                Binding="{Binding ElementName=DockSite, Path=ToolItemContainerStyle}"
                Comparison="NotEqual"
                Value="{x:Null}">
                <behaviors:ChangePropertyAction PropertyName="ToolItemsSource" Value="{Binding Items}" />
            </behaviors:DataTrigger>
        </behaviors:Interaction.Triggers>
        <docking:SplitContainer>
            <docking:SplitContainer>
                <docking:ToolWindowContainer />
            </docking:SplitContainer>
        </docking:SplitContainer>
    </controls:SlotGroupDockSite>
</DataTemplate>

Writing code to bind ToolItemsSource after changing the ToolItemContainerStyle property can resolve the issue. However, I would appreciate it if you could confirm and address this problem.