C# .NET blazor mudblazor drag and drop problem

When I drag an item to a higher place(it means lower position index) its working fine(in the same Section), but if I try to a lower place(it means higher position index)(in the same Section) nothing happening.

MudCoantainer ItemDropped method:

private void ItemUpdated(MudItemDropInfo<DropZoneItem> dropItem){    dropItem.Item.Zone = dropItem.DropzoneIdentifier;    var indexOffset = _items.Count(x => x.Zone == dropItem.DropzoneIdentifier);    var actualId = 0;    if (Key == "edit" && dropItem.Item.Zone == "_header")    {        foreach (var item in _section)        {            if (item.DocumentId == doc.Id && item.Name == "_header")            {                actualId = item.Id;            }        }    }    foreach (var actualSection in sections)    {        if (actualSection.DocumentId == doc.Id)        {            if (actualSection.Name == dropItem.DropzoneIdentifier)            {                actualId = actualSection.Id;            }        }    }    var itemToUpdate = _items.FirstOrDefault(item => item.Id == dropItem.Item.Id);    if (itemToUpdate != null)    {                    itemToUpdate.SectionId = actualId;    }    foreach (var item in sections)    {        if (dropItem.Item.Zone == item.Name)        {            dropItem.Item.SectionPosition = item.Position;            dropItem.Item.SectionId = item.Id;        }    }    _items.UpdateOrder(dropItem, item => item.Position, indexOffset);    _items = _items.OrderBy(x => x.Position).Select(item => new DropZoneItem        {            Id = item.Id,            Zone = item.Zone,            Name = item.Name,            Type = item.Type,            Description = item.Description,            Position = item.Position,            SectionId = item.SectionId,            EnabledValue = item.EnabledValue,            SectionPosition = item.SectionPosition        })    .ToList();}

Note: I need this method, because i need to update _items list and something else.

I tried different ways, but i dont know whats the problem.