Cómo incluir valores NULL en una consulta con Outer Join y Group By

Hubo un pequeño error en su consulta usando count. Esto funciona.

select count(ui.item_id) as total, in.item_desc
from   item_name `in`
       left join user_items ui on ui.item_id = in.item_id
                                        and ui.user_id in (127, 128)
group by
       in.item_desc
order by total desc