Some Items of ViewModel get lost between View and controller - asp.net-mvc-4

Question

the problem is, that my ViewModel has e.g. 12 items. In the Chrome-Browser i can see (Network--> klick on the postback request --> Headers--> Form Data), that all 12 items have modified values, that i want to save in the controller. But in the controller there are just 9 items that have content arriving. Where are the other three? The Capacity of the Model is 16 but the other items from 9 to 15 are set to null.
How can i find out what happens between the view and controller during the postback?
Update
Ok, now i found out that the ModelState doesnt contains all Items, but the Information will be transfered to the controller in the Request --> Form container. Let see, how the missing items will also be transfered to the ModelState...
ViewModel
public class ViewModel
{
public List<tool.Models.Issue> OpenIssue { get; set; }
public List<tool.Models.Issue> AllIssuesExceptOriginal { get; set; }
public List<tool.Models.Issue> ClosedIssue { get; set; }
public tool.Models.Site Site { get; set; }
public int ID { get; set; }
}
Controller
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Edit( ViewModels.ViewModel ViewModel)
{
//Do something with the content of the ViewModel
}
View (a lot more complex)
#for (int i = 0; i < Model.OpenIssue.Count(); i++)
{
#Html.HiddenFor(modelItem => modelItem.OpenIssue[i].Id);
//a lot more HiddenFor fields
Model.AllIssuesExceptOriginal.Capacity = Model.AllIssuesExceptOriginal.Count;
var History = Model.OpenIssue[i].Histories.Where(p => p.IssueId == Model.OpenIssue[i].Id).OrderByDescending(a => a.LastUpdate).First();
<tr class="Content_table">
<td class="Content_Column">
<div class="Content_all">
<div class="History">#Html.DisplayFor(modelItem => History.Description)</div>
#if( Model.AllIssuesExceptOriginal.Where(p => p.InternalNotes.Replace("Updated:", "") == Model.OpenIssue[i].Id.ToString()).Count() != null)
{
for (int a = 0; a < Model.AllIssuesExceptOriginal.Where(p => p.InternalNotes.Replace("Updated:", "") == Model.OpenIssue[i].Id.ToString()).Except(Model.AllIssuesExceptOriginal.Where(l=>l.LastUpdate == DateTime.MinValue)).Count(); a++)
{
var OtherIssues = Model.AllIssuesExceptOriginal.Where(p => p.InternalNotes.Replace("Updated:", "") == Model.OpenIssue[i].Id.ToString()).Except(Model.AllIssuesExceptOriginal.Where(l=>l.LastUpdate == DateTime.MinValue)).OrderBy(p => p.LastUpdate).ToList();
if(OtherIssues[a].Description != "noUpdate")
{
<div class="updated" style="position:relative" id="#i:#a:Description">
<b>#Html.DisplayFor(modelitem=> OtherIssues[a].User.FirstName) #Html.DisplayFor(modelitem=> OtherIssues[a].User.LastName)</b> <span style="color:grey;">-#Html.ValueFor(modelitem=> OtherIssues[a].LastUpdate, "{0:dd.MM.yy HH:mm}") </span> <br />
#Html.DisplayFor(modelItem => OtherIssues[a].Description, new { #class = "meeting" })
<span style="float:right; "><img src="~/Images/ic_cancel_black_18dp.png" id="Description:#i:#a:#Model.AllIssuesExceptOriginal.FindIndex(p=>p.Id == OtherIssues[a].Id)" onclick="markActiveLinkDelete(this);">
#Html.HiddenFor(modelItem => modelItem.AllIssuesExceptOriginal[Model.AllIssuesExceptOriginal.FindIndex(p=>p.Id == OtherIssues[a].Id)].Description)
</span>
</div>
}
}
}
<div class="updated" >#Html.TextAreaFor(modelItem => modelItem.AllIssuesExceptOriginal[Model.AllIssuesExceptOriginal.FindLastIndex(p=>p.InternalNotes.Replace("Updated:","") == Model.OpenIssue[i].Id.ToString())].Description, new { #class = "meeting" })</div>
#Html.HiddenFor(modelItem=>modelItem.AllIssuesExceptOriginal[Model.AllIssuesExceptOriginal.FindLastIndex(p=>p.InternalNotes.Replace("Updated:","") == Model.OpenIssue[i].Id.ToString())].InternalNotes)
</div>
</td>
}
</table>
</div>
<p>
<input type="submit" value="Save" name = "Save"/>
<input type="submit" value="Cancel" name = "Cancel"/>
</p>
</fieldset>
}
Thanks for your help in advance.

Answer 1

To solve this, i added a Hidden field with the indexer for each item of the Model.
View Updated
#if( Model.AllIssuesExceptOriginal.Where(p => p.InternalNotes.Replace("Updated:", "") == Model.OpenIssue[i].Id.ToString()).Count() != null)
{
for (int a = 0; a < Model.AllIssuesExceptOriginal.Where(p => p.InternalNotes.Replace("Updated:", "") == Model.OpenIssue[i].Id.ToString()).Except(Model.AllIssuesExceptOriginal.Where(l=>l.LastUpdate == DateTime.MinValue)).Count(); a++)
{
var OtherIssues = Model.AllIssuesExceptOriginal.Where(p => p.InternalNotes.Replace("Updated:", "") == Model.OpenIssue[i].Id.ToString()).Except(Model.AllIssuesExceptOriginal.Where(l=>l.LastUpdate == DateTime.MinValue)).OrderBy(p => p.LastUpdate).ToList();
if(OtherIssues[a].Description != "noUpdate")
{
//content
}
//This is new
#Html.HiddenFor(modelItem => modelItem.AllIssuesExceptOriginal[Model.AllIssuesExceptOriginal.FindIndex(p=>p.Id == OtherIssues[a].Id)].Id)
}
}