SQLite Xamarin.forms不返回保存的数据

using SQLite;
using System;
using Xamarin.Forms;

public class Item
{
    [PrimaryKey, AutoIncrement]
    public int Id { get; set; }
    public string Text { get; set; }
}

public class DatabaseContext : SQLiteConnection
{
    public DatabaseContext(string path) : base(path)
    {
    }

    public DbSet<Item> Items { get; set; }
}

public class MainPage : ContentPage
{
    private readonly DatabaseContext _database;

    public MainPage()
    {
        _database = new DatabaseContext(System.IO.Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Personal), "items.db3"));

        var saveButton = new Button { Text = "Save Item" };
        saveButton.Clicked += async (sender, e) =>
        {
            var newItem = new Item { Text = "New Item" };
            _database.Insert(newItem);
            await DisplayAlert("Success", "Item saved.", "OK");
        };

        var listView = new ListView();
        listView.ItemsSource = _database.Table<Item>().ToList();

        Content = new StackLayout
        {
            Children = { saveButton, listView }
        };
    }
}