POST controller action method is having a LIST return with count=0

This is a simple problem and I've look at all answer(There is a quite a few) that are related and compared my code to it and I can't see where I'm going wrong.

Controller

        [HttpGet]
        public ActionResult PatInformation(long id)
        {
            if (ModelState.IsValid)
            {
                var patient = db.tblPatients.Find(id);

                PatientViewModels patientVM = _mapper.Map<PatientViewModels>(patient);

                return View(patientVM);
            }
            return RedirectToAction("Index");
        }

        [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult PatientInformation(PatientViewModels model)
        {
            if (!ModelState.IsValid)
            {
                return View(model);
            }

            tblPatient tblPatient = db.tblPatients.Find(model.PatientID);

            tblPatient.Forename1 = model.Forename1;
            tblPatient.Surname = model.Surname;

            db.Entry(tblPatient).State = EntityState.Modified;
            db.SaveChanges();

            PatientViewModels patientsVM = _mapper.Map<PatientViewModels>(tblPatient);

            return View("PatientInformation", patientsVM);

ViewModel

    public class PatientViewModels
    {
        public PatientViewModels()
        {
            tblTumours = new List<TumoursViewModel>();
            tblGP = new tblGP();
            tblAddress = new tblAddress();
        }

        public long PatientID { get; set; }

        public long? HSCNO { get; set; }

        public string Surname { get; set; }
        public string Forename1 { get; set; }
        public string Forename2 { get; set; }
        public string PrevName { get; set; }
        public long? PatAddress { get; set; }
        public long? PatGP { get; set; }
        public string BirthGender { get; set; }
        public DateTime? DOB { get; set; }
        public double? Ethnic { get; set; }
        public string VitalStatus { get; set; }
        public DateTime? DateCreated { get; set; }
        public DateTime? DateAmended { get; set; }
        public double? OldID { get; set; }
        public long? NICRNumber { get; set; }
        public virtual tblAddress tblAddress { get; set; }
        public virtual tblGP tblGP { get; set; }
        public virtual List<TumoursViewModel> tblTumours { get; set; } 
        public string FullAddress { get; set; }
        public string Age { get; set; }
    }

    public class TumoursViewModel
    {
        public long TumourID { get; set; }
        public Nullable<double> TumourNo { get; set; }
        public Nullable<long> PatientID { get; set; }
        public string ICD03 { get; set; }
        public string ICD10 { get; set; }
        public virtual tblMorphology tblMorphology { get; set; }
        public virtual tblBehaviour tblBehaviour { get; set; }
        public virtual tblAddress tblAddress { get; set; }
        public Nullable<System.DateTime> DateOfDiag { get; set; }
        public string Metastases { get; set; }
        public string TumourStatus { get; set; }
        public Nullable<double> StageGrade { get; set; }
        public PatientViewModels Patients { get; set; }
    }

<table id="tblTumours" class="table">
    <thead>
        <tr>
            <th>Tumour Id</th>
            <th>ICD03 Site</th>
            <th>ICD10 Site</th>
            <th>Morphology</th>
            <th>Behaviour</th>
            <th>Diagnosis</th>
            <th>Method</th>
            <th>Status</th>
            <th>Final Stage / Complate</th>
        </tr>
    </thead>
    <tbody>

        @for (int i = 0; i < Model.tblTumours.Count; i++)
        {
        <tr class="table-row" data-href="@Url.Action(" TumourInformation", "Tumours" , new { tumourId=Model.tblTumours[i].TumourID, patientId=Model.PatientID })">
            <td class="pt-3-half" hidden="true">@Html.TextBoxFor(m => Model.tblTumours[i].TumourID, new { Class = "form-control" })</td>
            <td class="pt-3-half">@Html.TextBoxFor(m => Model.tblTumours[i].TumourNo, new { Class = "form-control" })</td>
            <td class="pt-3-half">@Html.HiddenFor(m => Model.tblTumours[i].ICD03, new { Class = "form-control" })</td>
            <td class="pt-3-half">@Html.TextBoxFor(m => Model.tblTumours[i].ICD03, new { Class = "form-control" })</td>
            <td class="pt-3-half">@Html.TextBoxFor(m => Model.tblTumours[i].ICD10, new { Class = "form-control" })</td>
            <td class="pt-3-half">@Html.TextBoxFor(m => Model.tblTumours[i].tblMorphology.morphology_code, new { Class = "form-control" })</td>
            <td class="pt-3-half">@Html.TextBoxFor(m => Model.tblTumours[i].tblBehaviour.BehaviourCode, new { Class = "form-control" })</td>
            <td class="pt-3-half">@Html.TextBoxFor(m => Model.tblTumours[i].DateOfDiag, new { Class = "form-control" })</td>
            <td class="pt-3-half">@Html.TextBoxFor(m => Model.tblTumours[i].Metastases, new { Class = "form-control" })</td>
            <td class="pt-3-half"><span class="badge badge-warning">@Html.TextBoxFor(m => Model.tblTumours[i].TumourStatus, new { Class = "form-control" })</span></td>
            <td class="pt-3-half">@Html.TextBoxFor(m => Model.tblTumours[i].StageGrade, new { Class = "form-control" })</td>
        </tr>
        }


    </tbody>
</table>

When I post the controller with tblTumours List always returns the as count=0. I'm sure this is a simple fix but I just can't see it.

Hopefully someone can help and please bare with as I just started as a developer and inherited this. Thanks!