Based on discussion https://wpftoolkit.codeplex.com/discussions/534906.
When a CheckComboBox is used in a DataTemplate, has a SelectedValue and its Delimiter is something else than a coma, the selectedValue is not active when loaded.
When a CheckComboBox is used in a DataTemplate, has a SelectedValue and its Delimiter is something else than a coma, the selectedValue is not active when loaded.