Id always null when use input type=“hidden” ASP-for="itemid"

namespace books.BL
{
    public class ClsItem
    {
        public  StoreBooksContext booksContext=new StoreBooksContext();      

        public List<tbitem> GetAll()
        {
        
            List<tbitem> lstItems = booksContext.TbItems.
                OrderByDescending(a => a.ItemName).
                ThenByDescending(a => a.SalePrice).ToList();
            return lstItems;
        }

        public TbItem GetById(int id)
        {
            TbItem SelectedItem = booksContext.TbItems.FirstOrDefault(i => i.ItemId == id);
            return SelectedItem;
         
        }

        public bool AddToDataBase(TbItem item)
        {

            try
            {
                booksContext.TbItems.Add(item);
                booksContext.SaveChanges();
                return true;
            }
            catch (Exception)
            {

                throw;
            }
        }

        public bool Edit(TbItem item)
        {

            try
            {

                booksContext.Entry(item).State = EntityState.Modified;
                booksContext.SaveChanges();
                return true;
            }
            catch (Exception)
            {

                throw;
            }
        }
    }
}

namespace books.Areas.Admin.Controllers
{
    [Area("Admin")]
    public class ItemsController : Controller
    {
        public ClsItem clsItem = new ClsItem();

        public IActionResult List()
        {

            return View(clsItem.GetAll());
        }

        public IActionResult Edit(int? id)
        {
            ClsCategories clsCategories = new ClsCategories();
            ViewBag.clsCategoryList = clsCategories.GetAll();
            if (id != null)
            {
                return View(clsItem.GetById(Convert.ToInt32(id)));
            }
            else
            {
                return View();
            }

        }


     
        [HttpPost]
        public async Task <iactionresult> Save(TbItem item,List<iformfile> Files)
        {

            try
            {
                if (ModelState.IsValid)
                {

                    foreach (var file in Files)
                    {
                        if (file != null)
                        {
                            string ImageName = Guid.NewGuid().ToString() + ".jpg";
                            var filePaths = Path.Combine(Directory.GetCurrentDirectory(), @"wwwroot\Uploads", ImageName);
                            using (var stream = System.IO.File.Create(filePaths))
                            {
                                await file.CopyToAsync(stream);
                            }
                            item.ImageName = ImageName;
                        }
                    }

                    if (item.ItemId == 0)
                        clsItem.AddToDataBase(item);
                           
                    else
                    
                        clsItem.Edit(item);
                        return RedirectToAction("List", "Items");
                    
                }

                return RedirectToAction("List", "Items");
            }
            catch (Exception ex)
            {

                throw ex;
            }

        }
    }
}