[ListView] Add item after page constructor made label appear empty

Hi Xamarin !

I have a very difficult problem.
I have a ListView with grouping and lot of DataTemplate. I need to add item in this list when user execute an action.
The row I need to add have a label and a Switch, but when I add this item, the row appear with the Switch but the label appear empty.

I work on this since 3 hours and I didn't find any solution (so bad).

This is the source code (I've simplify at maximum) :

Model and grouping :
`
public enum ModelType {
BASE, CHECKBOX, TEXT
}

public class NewHorseEntryModel : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged; // I use Fody here, but it isn't important

        public ModelType Type { get; set; }

        public string Field { get; set; }
        public string Value { get; set; }

        public bool Checked { get; set; }

        public static NewHorseEntryModel NewBase(string id, string field, string value, string image=null) {
                return new NewHorseEntryModel() { FieldID = id, Field = field, Value = value, ImageSource=image, Type = ModelType.BASE };
        }

        public static NewHorseEntryModel NewText(string id, string field, string value, string image = null)
        {
                return new NewHorseEntryModel() { FieldID = id, Field = field, Value = value, ImageSource = image, Type = ModelType.TEXT };
        }

        public static NewHorseEntryModel NewCheckbox(string id, string field, bool isChecked)
        {
                return new NewHorseEntryModel() { FieldID = id, Field = field, Checked = isChecked, Type = ModelType.CHECKBOX };
         }
    }

    public class EntryGroup : ObservableCollection<NewHorseEntryModel>
    {
    public string Title { get; set; }

        public EntryGroup(string title)
        {
                Title = title;
        }
 }

`

The code of the page who show the listView :
`
public partial class NewHorsePage : ContentPage
{
public ObservableCollection AllItems { private set; get; }

        public NewHorsePage(Cheval cheval=null)
        {
                InitializeComponent();

                listView.HasUnevenRows = true;
                listView.ItemSelected += ItemSelected;

                AllItems = new ObservableCollection<EntryGroup> {
                    new EntryGroup ("CARACTERISTIQUES") {
                            NewHorseEntryModel.NewBase("race", "RACE", "Auxois"),
                            NewHorseEntryModel.NewBase("robe", "ROBE", "Alezan"),
                            NewHorseEntryModel.NewBase("sexe", "SEXE", "Male")
                    },
                    new EntryGroup ("GROUPE") {
                            NewHorseEntryModel.NewBase("groupe")
                    },
                };

        // the variable groupGroup represent the EntryGroup who are named "GROUPE"
        groupGroup.Insert(0, NewHorseEntryModel.NewCheckbox("groupe1","GROUPE1", false)); // It's work

                listView.BindingContext = this;
                listView.SetBinding(ListView.ItemsSourceProperty, "AllItems");

        // In the constructor if I call this, since I have already bind ItemsSource, it's work : 
        groupGroup.Insert(0, NewHorseEntryModel.NewCheckbox("groupe1","GROUPE1", false)); // It's work
        }

        void ItemSelected(object sender, SelectedItemChangedEventArgs e)
        {
        // !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
        // !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! SEE HERE !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
        // !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
        // !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

                // The real problem is here : the row appear but the label is shown empty (the Switch appear correctly)
        // If I check the Field property (who are binded to the label in XAML) I got the good value ("GROUPE1")
        groupGroup.Insert(0, NewHorseEntryModel.NewCheckbox("groupe1","GROUPE1", false)); // It's work

        // NOTE : If I set the Text of the label at "Test" for example (so without binding), the result is the same : the text doesn't appear
         }
 }

`

So if you have some idea to help me ...

Thanks, and sorry if you didn't understand me very well, english is a lot difficult for me.

Note : I've also try to do :
listView.ItemsSource = null; listView.ItemsSource = AllItems;
But without success.