Object value is null after deserialization (Xamarin with SQLite) - sqlite

Question

for an internship project I'm developping an app with Xamarin that will allow users to scan barcodes and create sheets of labels and purchases.
To prevent the scanned codes from being lost in case of crash etc, I've implemented SQLite to create a local backup that we could restore.
The structure is as follows : a ListOfLabelLines contains several LabelLine which each contain a Product and different other informations (such as packaging, quantity etc).
ListOfLabelLines.cs :
[Table("ListOfLabelLines")] // Indique le nom de la table qui sera générée par SQLite
public class ListOfLabelLines : BaseItem
{
private string _name { get; set; }
[TextBlob("LabelLinesBlob")]
public ObservableCollection<LabelLine> lines { get; set; }
[TextBlob("ListBlob")]
public List<String> TestList { get; set; }
public string LabelLinesBlob { get; set; } // serialized LabelLines
public string ListBlob { get; set; } // serialized TestList
public ListOfLabelLines()
{
}
public ListOfLabelLines(string name)
{
this._name = name;
lines = new ObservableCollection<LabelLine>();
TestList = new List<String>();
TestList.Add("Test1");
TestList.Add("Test2");
}
public string Name
{
get { return _name; }
set
{
_name = value;
}
}
}
}
These objects ListOfLabelLines contain an ObservableCollection<LabelLine> which I'm serializing by using the TextBlob property from SQLite-net-extensions.
However, when I retrieve the ListOfLabelLines I've stored, the ObservableCollection appears as null :
Example of null collections
Here are the methods I use to store the objects in SQlite :
public void SaveListOfLabelLines(ListOfLabelLines ShelfLabelInstance)
{
var query = from label in database.Table<ListOfLabelLines>()
where label.Name == ShelfLabelInstance.Name
select label;
var res = query.FirstOrDefault();
if (res != null)
{
database.UpdateWithChildren(ShelfLabelInstance);
Console.WriteLine("Label " + ShelfLabelInstance.Name + " updated");
}
else
{
database.InsertWithChildren(ShelfLabelInstance);
Console.WriteLine("Label " + ShelfLabelInstance.Name + " created");
}
}
and to retrieve them :
public void CheckProductsInLabelLine(string n)
{
var query = from LOLL in database.Table<ListOfLabelLines>()
where LOLL.Name == n
select LOLL;
ListOfLabelLines res = query.FirstOrDefault();
The string property linked to the TextBlob, however, contains the JSON object I need.
I thought the ObservableCollection would be obtainable when getting the object in DB since TextBlob is supposed to serialize AND deserialize.
Could anybody help ?
Thanks a lot !