RadDataGrid with specific Columns, Aggregation and Grouping in C#

I am having an issue with a custom defined datagrid with specific columns, aggregation and grouping and it does not work...well, not in C#. The grouping works 100% if defined in XAML, but its hit and miss for c#, mostly miss.

Aggregation has never worked.

I am basically generating PivotItems... which works, and then I am populating each pivot with a datagrid with the specific columns defined, as well as Grouping and Aggregation rules.

The population of the PivotItems, DataGrids and the Data all work perfectly except the Aggregation and Grouping.

I have even tried using a XAML template... also doesn't work, so I am at a loss.

Could someone please provide some tips as to what I am doing wrong.
Any help or suggestions would be greatly appreciated.

Thanks

My Code is below:

private void BuildPivots()
{
    if (App.Categories != null)
    {
        foreach (Categories Category in App.Categories)
        {
            Home_PivotShell.Items.Add(new PivotItem
            {
                Header = Category.Name,
                Name = Category.Id,
                Content = new RadDataGrid
                {
                    AutoGenerateColumns = false,
                    UserEditMode = DataGridUserEditMode.External,
                    ItemsSource = App.DataSet.Where(x => x.CategoryId == Category.Id),
                    GroupDescriptors =
                    {
                        new PropertyGroupDescriptor() { PropertyName = "Name", DisplayContent = "Description"}
                    },
                    AggregateDescriptors =
                    {
                        new PropertyAggregateDescriptor() { PropertyName = "Column1", Function = KnownFunction.Count}
                    },
                    Columns =
                    {
                        new DataGridTextColumn() { PropertyName = "Name", Header = "Description" },
                        new DataGridTextColumn() { PropertyName = "Column1" },
                        new DataGridTextColumn() { PropertyName = "Column2" },
                        new DataGridTextColumn() { PropertyName = "Column3" },
                        new DataGridTextColumn() { PropertyName = "Column4" },
                        new DataGridTextColumn() { PropertyName = "Column5" },
                        new DataGridTextColumn() { PropertyName = "Column6" },
                        new DataGridTextColumn() { PropertyName = "Column7" },
                    }
                }
            });
        }
    }
}

DataSource (As Requested):

NOTE: Problem is not with the datasource, I have several datasources to play with and they all do the same thing, Grouping works on XAML not on C#. Aggregation does not work at all.

namespace MyUWPApp.DataObjects
{
    public class DataSet
    {
        public string Name { get; set; }
        public string Column1 { get; set; }
        public string Column2 { get; set; }
        public string Column3 { get; set; }
        public string Column4 { get; set; }
        public string Column5 { get; set; }
        public string Column6 { get; set; }
        public string Column7 { get; set; }
    }
}