Expandable ListView showing all items already expanded/open

Hi,
I am implementing Expandable ListView in xamarin.forms,. But the listview showing all items expanded.
See my code below

 public class MainListView
    {

        private Product _oldProduct;
        public ObservableCollection<Product> Products { get; set; }

        public MainListView()
        {
            Products = new ObservableCollection<Product>
            {
                new Product
                {
                    Title = "Microsoft 650",
                    IsVisible = false
                },
            };
        }

        public void ShoworHiddenProducts(Product product)
        {
            if (_oldProduct == product)
            {
                product.IsVisible = !product.IsVisible;
                UpDateProducts(product);
            }
            else
            {
                if (_oldProduct != null)
                {
                    _oldProduct.IsVisible = false;
                    UpDateProducts(_oldProduct);

                }
                product.IsVisible = true;
                UpDateProducts(product);
            }
            _oldProduct = product;
        }

        private void UpDateProducts(Product product)
        {
            var Index = Products.IndexOf(product);
            Products.Remove(product);
            Products.Insert(Index, product);

        }
    }

 public class Product
    {
        public string Title { get; set; }
        public bool IsVisible { get; set; }
    }

Click event to open listview

    private void ListViewItem_Tabbed(object sender, ItemTappedEventArgs e)
        {
            var product = e.Item as Product;
            var vm = BindingContext as MainListView;
            vm?.ShoworHiddenProducts(product);
        }

This is xaml code

        <ListView Margin="0,0,0,0" 
              VerticalOptions="FillAndExpand"
              ItemTapped="ListViewItem_Tabbed"  
              ItemsSource="{Binding Products}"  
              HasUnevenRows="True"  
              BackgroundColor="Black">
            <ListView.ItemTemplate>
                <DataTemplate>
                    <ViewCell>
                        <StackLayout Padding="5">
                            <Label Text="{Binding Title}"  
                               FontSize="Medium"
                               TextColor="Azure"/>
                            <StackLayout IsVisible="{Binding Isvisible}"  
                                    Orientation="Horizontal"  
                                    Margin="0,0,0,0">
                                <Button Text="Place Order"  
                                    WidthRequest="110"  
                                    FontSize="Medium"  
                                    BackgroundColor="Chocolate"  
                                    TextColor="White"/>
                                <Button Text="Details"  
                                    WidthRequest="110"  
                                    FontSize="Medium"  
                                    BackgroundColor="CornflowerBlue"  
                                    TextColor="DarkBlue"/>
                                <Button Text="Edit"  
                                    WidthRequest="110"  
                                    FontSize="Medium"  
                                    BackgroundColor="LightCoral"  
                                    TextColor="Maroon"/>
                            </StackLayout>
                        </StackLayout>
                    </ViewCell>
                </DataTemplate>
            </ListView.ItemTemplate>
        </ListView>

For this implementation, I have followed below tutorial

https://www.c-sharpcorner.com/article/xamarin-forms-expendable-listview-app/