Doesn't deserialize one instance of an object

Question

I have a rather complex data model that gets serialized to and from XML. We all know that when C#'s XmlSerializer serializes the same instance of a object multiple times that objects data get duplicated. I am having an issue of one instance of an object not deserializing. For example, let's say we have three objects: A, B, C. Lets say that A contains two instances of B, and B contains an list of C.

A
->B
  ->List<C> -- This one deserializes
->B
  ->List<C> -- This one does not

When I deserialize object A, the first instance of B deserializes correctly. However, when I inspect the second instance of B the List<C> is empty. I have ran a difference compare on the sections XML and they are the same.

Does anyone know why one list would deserialize and not the other?

UPDATE

This is the best that I can pair down the problem. The original XML is about 110,000 lines long.

Classes:

[Serializable]
public class A
{
    public B instanceOne {get; set;}
    public B instanceTwo {get; set;}
}

[Serializable]
public class B : INotifyPropertyChanged
{
    private C _c;
    public ObservableCollection<C> C
    {
        get => _c;
        set
        {
            if(_c == value)
               return;
            _c = value;
            RaisePropertyChanged(nameof(C));
        }
   }
 //More Code
}

[Serializable, XmlRoot(ElementName = "MyC", Namespace = "MyNS")]
public class C
{
    public int value {get;set;}
}

XML output:

<?xml version="1.0"?>
<A xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <InstanceOne>
        <C>
          <Value xmlns="MyNS">10</Value>
        </C>
    </InstanceOne>
    <InstanceTwo>
        <C>
          <Value xmlns="MyNS">10</Value>
        </C>
    </InstanceTwo>
</A>

C# Deserialization Code

XmlSerializer xml = new XmlSerializer(typeof(A));

using (FileStream fs = File.OpenRead(@"C:\a.xml"))
{
    var t = xml.Deserialize(fs);
}

Answer 1

I was not able to solve the issue at hand by calling the XmlSerializer. I ended up parsing the file then going back through the XML with the XmlReader to fill in the specific missing gaps.