How to bind DataGridView to List <T> or BindingList <T>

I've done this a thousand times and it works, but now ... no :(

Am I doing something wrong here because nothing is showing in the grid?

namespace theGridIsNotWorking
{
using System;
using System.Collections.Generic;
using System.Windows.Forms;

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        var items = new List<Item>();

        items.Add(new Item(){ TheName = "first"});
        items.Add(new Item(){ TheName = "Second"});
        items.Add(new Item(){ TheName = "Third"});

        dataGridView1.DataSource = new List<Item>(items);
    }

    public class Item
    {
        public string TheName;
    }
}
}

      

        
        
        
      

    

Nothing special .... but very sad.