Controller Post action not getting view Model ASP.NET Core Razor pages

I am creating a razor form that takes options from a list from the model and displays radio buttons and a text input. when I submit, the post method has a view model where all properties are null. how can I fix it?

my razor view

@model CreateBallotViewModel
<div class="row">
    <div class="col-md-5 offset-md-1">
        <h4 class="mb-3">@Model.elect.Question</h4>
        <div class="my-3">
            @using (Html.BeginForm(actionName: "CreateBallot", controllerName: "Account", FormMethod.Post))
            {
                @foreach (var opt in Model.options)
                {
                    <div class="form-check">
                        @Html.RadioButtonFor(expression: model => model.choice, opt.OptionName, htmlAttributes: new { @class = "form-check-input" })
                        @*@Html.LabelFor(expression: model => @opt.OptionName, htmlAttributes: new { @class = "form-check-label" })
                        <input name="credit" asp-for="choice" type="radio" class="form-check-input" value="@opt.OptionName">*@
                        <label class="form-check-label" for="credit">@opt.OptionName</label>
                    </div>

                }
                <div class="form-check">
                    <input name="credit" asp-for="choice" type="radio" class="form-check-input" value="">
                    <label class="form-check-label" for="credit">Neutral</label>
                </div>
                <div class="col-md-3">
                    <label for="cc-cvv" class="form-label">Tracking Number</label>
                    <input type="text" class="form-control" id="cc-cvv" placeholder="" required="" asp-for="tracking">
                    <div class="invalid-feedback">
                        Security code required
                    </div>
                </div>
                <hr class="my-4">
                <button class="btn btn-primary" type="submit">Cast Ballot</button>
            }
        </div>
    </div>
</div>

My model

using System;
namespace electronicvotingfyp.Models
{
	public class CreateBallotViewModel
	{
		public List<ElectionOption> options { get; set; }
		public Election elect { get; set; }
		public string choice;
		public string tracking;
		//vote encrypted
		//signed vote
		//keys
	}
}

my controller with the get and post actions

 [Authorize]
        [HttpGet]
        public IActionResult CreateBallot(int ElectionId)
        {

            List<ElectionOption> electionOptions = new List<ElectionOption>();
            Election election = null;
            DbContextOptions<electronicvotingfypIdentityDbContext> options = new DbContextOptions<electronicvotingfypIdentityDbContext>();
            using (var db = new electronicvotingfypIdentityDbContext(options))
            {

                election = db.Elections.Single(u => u.ElectionId == ElectionId);
                electionOptions  = db.Options.Where(p => p.Election  == election).ToList();
            }

            CreateBallotViewModel cbm = new CreateBallotViewModel() { options = electionOptions ,elect = election };

            return View(cbm);
        }
        [Authorize]
        [HttpPost]
        public IActionResult CreateBallot(CreateBallotViewModel cbm)
        {
            ElectionKeySystem keys = null;
            DbContextOptions<electronicvotingfypIdentityDbContext> options = new DbContextOptions<electronicvotingfypIdentityDbContext>();
            using (var db = new electronicvotingfypIdentityDbContext(options))
            {

                keys = db.ElectionKeys.Single(u => u.RelatedElection.ElectionId == cbm.elect.ElectionId);
               
            }
            PemReader pr = new PemReader(new StringReader(keys.publicKey));
            AsymmetricCipherKeyPair keyPair = (AsymmetricCipherKeyPair)pr.ReadObject();
            //ElGamalPublicKeyParameters publicKeyParams = (ElGamalPublicKeyParameters)keyPair.Public;

            ElectionKeySystemContrroller ks = new ElectionKeySystemContrroller(keyPair);
            byte[] inputChoice = Encoding.UTF8.GetBytes(cbm.choice);
            byte[] inputTracking = Encoding.UTF8.GetBytes(cbm.tracking);
            byte[] encryptedChoice = ks.Encrypt(Encoding.UTF8.GetBytes(cbm.choice), 0, inputChoice.Length);

            return View(cbm);
        }
    }

I tried changing the form input which were initially html tags to Html.RadioFor. I also tried having new { enctype = "multipart/form-data" } as a parameter for Html.BeginForm. I also tried hidden fields for the properties I had set before.

Please give the getter and setter of properties

public string Tracking { get; set; }
public string Tracking { get; set; }

Agree with Nahid.

I reproduced your issue in my side and without {get; set;}, we can see in the request context that the form already submit data to the action but can't bind to the model.

By the way, in your controller you had cbm.elect.ElectionId, but in your form code, you didn't contain elect.ElectionId, so you also need to put code like this into the form, or the cbm.elect still be null.

@using (Html.BeginForm(actionName: "CreateBallot", controllerName: "home", FormMethod.Post))
            {
                <input style="display:none" asp-for="@Model.elect.ElectionId" />