WPF Update Datagrid Binding To ObservableCollection

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C#

.NET

WPF

Hi together,

i know that this is kind of a regular question but i am konfused on the behavior of my programm. I want to bind an observablecollection of custom objects to a datagrid. When the binding is done via code, after receiving the list over wcf, the datagrid shows the itemssource. But this doesn't work when i bind over xaml. i thought, that the observable collection automaticaly updates the datagrid over the collectionchangedevent. Here is my Code with a few comments:

public partial class AddressPage : Page
    {
        ObservableCollection<Address> AddressCollection =
        new ObservableCollection<Address>();
    
        public AddressPage()
        {
            this.LoadAddress();
            InitializeComponent();
        }

        private async void LoadAddress()
        {
            RestServiceClient client = new RestServiceClient();
            AddressCollection = await client.GetAddressAsync();
            MainGrid.ItemsSource = AddressCollection; //this works but i dont want it this way...
        }

        private void Button_Click_1(object sender, RoutedEventArgs e)
        {
            AddressCollection.Add(
            new Address { address1 = "test1", address2 = "test2" });
        }
    }

This is the XAML Code. The ItemsSource="{Binding AddressCollection}" is not working...

DataContext="{Binding RelativeSource={RelativeSource Self}}"
Style="{StaticResource standardDataPage}"
d:DesignHeight="300" d:DesignWidth="300"
Title="AddressPage">

<StackPanel>
<DataGrid x:Name="MainGrid" ItemsSource="{Binding AddressCollection}"  AutoGenerateColumns="False">
    <DataGrid.Columns>
        <DataGridTextColumn Header="address1" Binding="{Binding address1}"/>

Beside a few posts i read the comarison-articel:
List vs ObservableCollection vs INotifyPropertyChanged in Silverlight[^]
and the tutroial:
WPF DataGrid Practical Examples[^]
But i cant't get it...