The issue occurs in scenario when a custom TypeConverter is applied to the key structure.
It is possible to use the following List Editor as a workaround:
C#[ListEditor(typeof(object), true)]
public class MyASPxGridListEditor : ASPxGridListEditor {
public MyASPxGridListEditor(IModelListView model) : base(model) { }
public override void SetControlSelectedObjects(IList<object> objects) {
Grid.Selection.UnselectAll();
foreach (Object obj in objects) {
Object keyValue = ((WebDataSource)Grid.DataSource).View.GetKeyValue(obj);
if (KeyMembersInfo.Count > 1 && keyValue is List<Object>) {
keyValue = ((List<Object>)keyValue).ToArray();
}
Grid.Selection.SetSelection(Grid.FindVisibleIndexByKeyValue(keyValue), true);
}
}
}