web api .net core controller does not return correct data

In Visual Studio 2019, i have created an project with asp.net core project / angular template. Also added a model to create a web api controller crud with EF. These are model and controller code.

using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;

namespace BooksWebApiAng.Models
{
    public class Book
    {
        [Key]
        public int BookId { get; set; }
        [Column(TypeName = "nvarchar(40)")]
        public string Titulo { get; set; }
       [Column(TypeName = "nvarchar(40)")]
        public string Autor { get; set; }
        [Column(TypeName = "nvarchar(40)")]
        public string Editorial { get; set; }
    }
}

and for controller

using BooksWebApiAng.Models;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace BooksWebApiAng.Controllers
{
    [Route("[controller]")]
    [ApiController]
    public class BooksController : ControllerBase
    {
        private readonly BookContext _context;
        private readonly List<Book> books = new List<Book>();

        public BooksController(BookContext context)
        {
            _context = context;

            books.Add(new Book
            {
                BookId = 101,
                Titulo = "Tit1",
                Autor = "Aut1",
                Editorial = "Edi1"
            });
            books.Add(new Book
            {
                BookId = 102,
                Titulo = "Tit2",
                Autor = "Aut2",
                Editorial = "Edit2"
            });
            books.Add(new Book
            {
                BookId = 104,
                Titulo = "Tit2",
                Autor = "Aut3",
                Editorial = "Edit3"
            });
        }

      

       

        // Get list
        [HttpGet]
        public async Task<ActionResult<IEnumerable<Book>>> GetBooks()
        {
            var data = await _context.Books.ToListAsync();
                if (data == null)
                   return NotFound("No record");
                return (data);
                       
        }


        private async Task<List<Book>> DameBooks()
        {
            await Task.Delay(100).ConfigureAwait(false);
            return books;
        }
}

Then in Visual Studio with iis express when a call http://localhost/books it return a list with all books in book table, but when i publish in IIS 10 it doesn't, it return error trying parsing home page to json. But if a change line "var data = await _context.Books.ToListAsync();" to "var data = await DameBooks(); that just return the list books it works right both in iis express and IIS 10. Really i don't have any idea what happen, because debugging in both cases "data" variable had a list with object book. Thanks