TreeListBox only showing root, can i get some more help?

using ActiproSoftware.Windows;
using CommunityToolkit.Mvvm.ComponentModel;
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Input;
using System.Windows.Markup;
using System.Windows.Media;

namespace EmpirBus.Switching.FirmwareManager.App.Feature.Common
{
    [ContentProperty("Children")]    
    public partial class TreeNodeModel : ObservableObject
    {
        public ObservableCollection<TreeNodeModel> Children { get; set; } = new ObservableCollection<TreeNodeModel>();
        [ObservableProperty]
        private ICommand _defaultActionCommand;
        [ObservableProperty]
        private ImageSource _imageSource;
        [ObservableProperty]
        private bool _isDraggable = true;
        [ObservableProperty]
        private bool _isEditable;
        [ObservableProperty]
        private bool _isEditing;
        [ObservableProperty]
        private bool _isExpanded = true;
        [ObservableProperty]
        private bool _isLoading;
        [ObservableProperty]
        private bool _isSelectable = true;
        [ObservableProperty]
        private bool _isSelected;
        [ObservableProperty]
        private string _name;
        [ObservableProperty]
        private object _tag;
        /// <summary>
        /// The Firmware model
        /// </summary>
        [ObservableProperty]
        private object _innerModel;
    }
}

public class DefaultTreeListBoxItemAdapter : TreeListBoxItemAdapter
{

    public SortDescription? SortDescription { get; set; }

    public DefaultTreeListBoxItemAdapter()
    {
        this.ChildrenPath = "Children";
        this.IsEditingPath = "IsEditing";
        this.IsExpandedPath = "IsExpanded";
        this.IsLoadingPath = "IsLoading";
        this.IsSelectablePath = "IsSelectable";
        this.IsSelectedPath = "IsSelected";            
    }


    public override IEnumerable GetChildren(TreeListBox ownerControl, object item)
    {
        var model = item as TreeNodeModel;
        var enumerable = (model != null ? model.Children : null);

        if (this.SortDescription.HasValue)
        {
            var collectionViewSource = new CollectionViewSource()
            {
                SortDescriptions = {
                    this.SortDescription.Value
                },
                Source = enumerable,
            };
            return collectionViewSource.View;
        }

        return base.GetChildren(ownerControl, item);
    }

    public override ICommand GetDefaultActionCommand(TreeListBox ownerControl, object item)
    {
        var model = item as TreeNodeModel;
        return (model != null ? model.DefaultActionCommand : null);
    }

    public override bool GetIsDraggable(TreeListBox ownerControl, object item)
    {
        var model = item as TreeNodeModel;
        return (model != null ? model.IsDraggable : false);
    }

    public override bool GetIsEditable(TreeListBox ownerControl, object item)
    {
        var model = item as TreeNodeModel;
        return (model != null ? model.IsEditable : false);
    }

    public override bool GetIsEditing(TreeListBox ownerControl, object item)
    {
        var model = item as TreeNodeModel;
        return (model != null ? model.IsEditing : false);
    }

    public override bool GetIsExpanded(TreeListBox ownerControl, object item)
    {
        var model = item as TreeNodeModel;
        return (model != null ? model.IsExpanded : false);
    }

    public override bool GetIsLoading(TreeListBox ownerControl, object item)
    {
        var model = item as TreeNodeModel;
        return (model != null ? model.IsLoading : false);
    }

    public override bool GetIsSelectable(TreeListBox ownerControl, object item)
    {
        var model = item as TreeNodeModel;
        return (model != null ? model.IsSelectable : true);
    }

    public override bool GetIsSelected(TreeListBox ownerControl, object item)
    {
        var model = item as TreeNodeModel;
        return (model != null ? model.IsSelected : false);
    }

    public override string GetPath(TreeListBox ownerControl, object item)
    {
        var model = item as TreeNodeModel;
        return (model != null ? model.Name : null);
    }

    public override string GetSearchText(TreeListBox ownerControl, object item)
    {
        var model = item as TreeNodeModel;
        return (model != null ? model.Name : null);
    }

    public override void SetIsEditing(TreeListBox ownerControl, object item, bool value)
    {
        var model = item as TreeNodeModel;
        if (model != null)
            model.IsEditing = value;
    }

    public override void SetIsExpanded(TreeListBox ownerControl, object item, bool value)
    {
        var model = item as TreeNodeModel;
        if (model != null)
            model.IsExpanded = value;
    }

    public override void SetIsSelected(TreeListBox ownerControl, object item, bool value)
    {
        var model = item as TreeNodeModel;
        if (model != null)
            model.IsSelected = value;
    }

}

return base.GetChildren(ownerControl, item);