Razor类库中表单提交出现问题

@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers
@addTagHelper *, Volo.Abp.AspNetCore.Mvc.UI
@addTagHelper *, Volo.Abp.AspNetCore.Mvc.UI.Bootstrap
@addTagHelper *, Volo.Abp.AspNetCore.Mvc.UI.Bundling

@page
@using Volo.Abp.AspNetCore.Mvc.UI.Bootstrap.TagHelpers.Modal
@using Microsoft.Extensions.Localization
@using ITDog.Localization
@using ITDog.System.Area.Menu
@inject IStringLocalizer<ITDogResource> L
@model ITDog.System.Pages.Areas.Menu.Pages.EditModalModel
@{
     Layout = null;
}
<abp-dynamic-form abp-model="MenuDto" asp-page="/Areas/Menu/Pages/EditModal">
    <abp-modal>
        <abp-modal-header title="@L["UpdateMenu"].Value"></abp-modal-header>
        <abp-modal-body>
            <abp-input asp-for="Id" />
            <abp-form-content />
        </abp-modal-body>
        <abp-modal-footer buttons="@(AbpModalButtons.Cancel|AbpModalButtons.Save)"></abp-modal-footer>
    </abp-modal>
</abp-dynamic-form>

public class EditModalModel : ITDogPageModel
    {
        [HiddenInput]
        [BindProperty(SupportsGet = true)]
        public int Id { get; set; }

        /// <summary>
        /// 下拉项
        /// </summary>
        public List<SelectListItem> Menus { get; set; }

        /// <summary>
        /// 绑定项
        /// </summary>
        [BindProperty]
        public MenuDto MenuDto { get; set; }

        private readonly IMenuApplicationService _menuService;

        public EditModalModel(IMenuApplicationService menuService)
        {
            _menuService = menuService;
        }

        public async Task OnGetAsync()
        {
            var model = await _menuService.GetAsync(Id);
            MenuDto = ObjectMapper.Map<MenuModel, MenuDto>(model);

            var menuLookup = await _menuService.GetListAsync(new Volo.Abp.Application.Dtos.PagedAndSortedResultRequestDto() { MaxResultCount = 100, SkipCount = 0 });
            Menus = menuLookup.Items.Select(x => new SelectListItem(x.Name, x.Id.ToString())).ToList();
        }

        public async Task<IActionResult> OnPostAsync()
        {
            var dto = ObjectMapper.Map<MenuDto, MenuModel>(MenuDto);
            await _menuService.UpdateAsync(Id, dto);
            return NoContent();
        }
    }