PossibleAnimationBug.cs

public class TestPage : ContentPage
{
    ListView list;
    Button button;

    public TestPage()
    {
        list = new ListView { ItemsSource = new[] { "hello", "world", "from", "xamarin", "forms" } };

        button = new Button { Text = "Button" };

        // The same behavior happens for both Absolute and Relative layout.
        var layout = true ? Relative() : Absolute();

        Animate();

        Content = layout;
    }

    Layout Relative()
    {
        var layout = new RelativeLayout();
                   
        layout.Children.Add(list,
            Constraint.RelativeToParent(p => p.X),
            Constraint.RelativeToParent(p => p.Y),
            Constraint.RelativeToParent(p => p.Width),
            Constraint.RelativeToParent(p => p.Height)
        );
        
        layout.Children.Add(button, 
            Constraint.Constant(0),
            Constraint.Constant(300));

        return layout;
    }

    Layout Absolute()
    {
        var layout = new AbsoluteLayout { Children = { list, button } };

        AbsoluteLayout.SetLayoutBounds(list, new Rectangle(0, 0, AbsoluteLayout.AutoSize, AbsoluteLayout.AutoSize));
        AbsoluteLayout.SetLayoutBounds(button, new Rectangle(0, 300, AbsoluteLayout.AutoSize, AbsoluteLayout.AutoSize));

        return layout;
    }

    async void Animate()
    {
        // Comment this delay out to see the bug
        await Task.Delay(500);

        button.LayoutTo(new Rectangle(100, 100, 100, 100), 1000);
    }
}