Bug title Checkcombox绑定有问题

[dawndawnZyx]

Describe the bug

CheckComboBox多选框使用hc:ListBoxAttach.SelectedItems绑定选择项，会报警告找不到源: RelativeSource FindAncestor, AncestorType='HandyControl.Controls.TagContainer', AncestorLevel='1'。且绑定选择的内容可以通过后端更新，通过界面修改后传递过来的值就是null的了

Steps to reproduce the bug

<hc:CheckComboBox hc:InfoElement.ShowClearButton="True" hc:InfoElement.Title="筛选条件" hc:ListBoxAttach.SelectedItems="{Binding SelectConditions}" ItemsSource="{Binding FilterConditions}" ShowSelectAllButton="True" />

Expected behavior

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Screenshots

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NuGet package version

None

IDE

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Framework type

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Windows version

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Additional context

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