In your EditTemplate, you need to use a CellEditorBinding to bind the value of the IsChecked property.

You will need to provide a new CellEditor for each column that displays a nested property. Currently, the editor is trying to edit the ''master'' property and cannot resolve the nested one. Don't forget that you need to use the CellEditorBinding extension when linking a cell editor to its cell/column. You can find examples in the Cell Editors ...