ListView binding to ObservableCollection does not update GUI

Hi

Can anyone tell me why this simple code is not working as expected? Does the ListView control not listen for changes in the bound property?

• Expected: when I click the Add button, the GUI (ListView) updates through the binding and shows the new element in the ObservableCollection.
• Observed: GUI does not update but always shows the initial three items of the ObservableCollection.
• Btw: OnAddButtonClicked() does get called and ListViewItems does get updated (checked in the debugger). Calling OnPropertyChanged("ListViewItems") inside OnAddButtonClicked() did not help either.
• And: if I update the code as follows, the ListView works: add a Label control, bind that label to a 2nd property, update that property inside OnAddButtonClicked(), call OnPropertyChanged() from inside the property setter. So obviously this call to OnPropertyChanged() somehow triggers the ListView to get updated as well...
• I'm now using Xamarin.Forms version 1.1.0.6201. Didn't work with the previous version either.

XAML:

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="Test1.MainPage"
             Padding="10" Title="MainPageXaml">
    <StackLayout VerticalOptions="StartAndExpand" HorizontalOptions="Fill">
        <Button Text="Add" Clicked="OnAddButtonClicked" />
        <ListView ItemsSource="{Binding ListViewItems}" />
    </StackLayout>
</ContentPage>

C#:

public partial class MainPage : ContentPage
{
    public MainPage()
    {
        InitializeComponent();
        ListViewItems = new ObservableCollection<string> { "one", "two", "three" };
        BindingContext = this;
    }

    private void OnAddButtonClicked(object sender, EventArgs e)
    {
        ListViewItems.Add(DateTime.Now.ToString());
        // OnPropertyChanged("ListViewItems");
    }

    public ObservableCollection<string> ListViewItems { get; set; }
}

Markus