Propriedades vinculadas são sempre nulas

Eu tenho a seguinte página .NET Razor, não importa o que eu tente, nenhuma das propriedades parece vincular POSTe são todas nulas.

Quando olho para o objeto postado, todas as propriedades são nulas.

Auxiliares de tags estão incluídos

@page
@model AppointmentModel
@{
    ViewBag.Title = "Rendez-Vous";
    ViewBag.pTitle = "Rendez-Vous";
    ViewBag.pageTitle = "Accueil";
    Layout = "~/Views/Shared/_Layout.cshtml";
}
...
                <form id="formSubmit" method="post">
                    <div class="row">
                        <div class="col-md-6">
                            <div class="mb-3">
                                <label for="formrow-firstname-input" class="form-label">Prénom</label>
                                <input asp-for="Input.FirstName" type="text" class="form-control" id="formrow-firstname-input" placeholder="Entrez votre prénom" autocomplete="firstname" disabled>
                            </div>
                        </div>
                        <div class="col-md-6">
                            <div class="mb-3">
                                <label for="formrow-lastname-input" class="form-label">Nom de Famille</label>
                                <input asp-for="Input.LastName" class="form-control" autocomplete="lastname" aria-required="true" placeholder="Entrez votre nom de Famille" disabled />
                                
                            </div>
                        </div>
                    </div>
                    <div class="row">
                        <div class="col-md-6">
                            <div class="mb-3">
                                <label for="formrow-specialite" class="form-label">Cliniques</label>
                                <select id="formrow-specialite" asp-for="Input.Clinic" asp-items="Model.Locations" class="form-select"></select>
                            </div>
                        </div>
                    </div>
                    <div class="row">
                        <div class="col-md-6">
                            <div class="mb-3">
                                <label>Date désirée du rendez-vous</label>
                                <div class="input-group" id="datepicker2">
                                    <input type="text" class="form-control" placeholder="dd M, yyyy"
                                           data-date-format="dd M, yyyy" data-date-container='#datepicker2' data-provide="datepicker"
                                           data-date-autoclose="true">

                                    <span class="input-group-text"><i class="mdi mdi-calendar"></i></span>
                                </div><!-- input-group -->
                            </div>
                        </div>
                        <div class="col-md-6">
                            <div class="mb-3">
                                <label for="formrow-periode" class="form-label">Période de la journée</label>
                                <select id="formrow-periode" class="form-select">
                                    <option>Matin</option>
                                    <option>Après-Midi</option>
                                </select>
                            </div>
                        </div>
                    </div>
                    <div class="row">

                        <div class="col-md-6">
                            <div class="mb-3">
                                <label for="formrow-email-input" class="form-label">Courriel</label>
                                <input asp-for="Input.Email" type="email" class="form-control" id="formrow-email-input" placeholder="Courriel" disabled>
                            </div>
                        </div>
                    </div>
                    <div class="row">

                        <div class="col-md-6">
                            <div class="mb-3">
                                <label for="formrow-email-input" class="form-label">Raison de votre visite</label>
                                <textarea class="form-control" id="formrow-email-input" placeholder="Riason de votre visite"></textarea>
                            </div>
                        </div>
                    </div>
                    <div>
                        <button type="submit" id="btnSubmit" class="btn btn-primary w-md">Soumettre</button>
        ...
</div>
}

Tentei criar uma classe separada e passei quase uma hora depurando. Tentei colocar no corpo, nada funciona. Estou no .NET 7.

Esta é minha aula

using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Identity.EntityFrameworkCore;
using Microsoft.AspNetCore.Identity.UI.Services;
using Microsoft.AspNetCore.Mvc;
#nullable disable
using Microsoft.AspNetCore.Mvc.RazorPages;
using Microsoft.AspNetCore.Mvc.Rendering;
using System.ComponentModel.DataAnnotations;

namespace CBQAdmin.Pages
{
    [Authorize]
    public class AppointmentModel : PageModel
    {
        private readonly CBQAdminIContext _context;
        private readonly UserManager<CBQIdentityUser> _userManager;
        private readonly ILogger<AppointmentModel> _logger;
     
        [BindProperty]
        public InputModel Input { get; set; }
        
        public SelectList Locations { get; set; } 

        public AppointmentModel(
            UserManager<CBQIdentityUser> userManager,
            ILogger<AppointmentModel> logger,
            CBQAdminIContext context)
        {
            _userManager = userManager;
            _logger = logger;
            _context = context;
        }

        public class InputModel
        {
            [DataType(DataType.Text)] 
            public string FirstName { get; set; }

            [DataType(DataType.Text)]
            public string LastName { get; set; }

            [DataType(DataType.Text)] 
            public string Email { get; set; }

            [DataType(DataType.Text)]
            public string Clinic { get; set; }

            [DataType(DataType.Text)]
            public string PolicyNumber { get; set; }
            
            [DataType(DataType.Text)]
            public string Reason { get; set; }
        }

        public async Task OnGetAsync()
        {
            Locations = new SelectList(_context.Clinics.OrderBy(n => n.Name).ToList(), "Name", "Name");
            var user = await _userManager.GetUserAsync(User);
            Input = new InputModel();

            if (user != null)
            {
                Input.Email = await _userManager.GetEmailAsync(user);

                if (!string.IsNullOrEmpty(user.FirstName))
                {
                    Input.FirstName = user.FirstName;
                }

                if (!string.IsNullOrEmpty(user.LastName))
                {
                    Input.LastName = user.LastName;
                }

                if (!string.IsNullOrEmpty(user.PolicyNumber))
                {
                    Input.PolicyNumber = user.PolicyNumber;
                }
            }
        }

        public async Task<IActionResult> OnPostAsync()
        {
            var user = await _userManager.GetUserAsync(User);

            InputModel input = new InputModel();

            await TryUpdateModelAsync<InputModel>(
                input, "input", i => i.FirstName, i => i.LastName, i => i.PolicyNumber, i => i.Clinic, i => i.Reason);                 

            if (ModelState.IsValid)
            {
                if (user != null)
                {
                    EmailService emailService = new EmailService();
                    await emailService.SendAppointmentRequest(Input);
                }
            }

            return Page();
        }
    }
}