ASP.NET Core EF set @html as input source

Question

I don't understand why the table adds only one value and it doesn't add the second one. For the HazardClass is working fine but for HazardDetails is not

 

Update. It seems that the problem I have is with:

 

<div class="form-control">
                @Html.DisplayFor(model => model.HazardClass.IdHC)
            </div>

which also should be source for input

 

var emptyHaz = new HazardDetail();

            if (await TryUpdateModelAsync<HazardDetail>(emptyHaz, "hazardDetail", s => s.IdHC, s => s.HazDetail))
            {
                _context.HazardDetails.Add(emptyHaz);
                await _context.SaveChangesAsync();
                return RedirectToPage("./Index");
            }

So, the question is, how do I get the @html..... to be input  for IdHC?