After upgrading from 1.11, lost visibility of all orders in back-end. Tracked
down problem to line 125 in function.orders_tab.php:
++++ original code: ++++
LEFT JOIN
(SELECT order_id, SUM(quantity) AS items FROM
'.cms_db_prefix().'module_orders_items
WHERE item_type = \''.line_item::ITEMTYPE_PRODUCT.'\' OR
item_type = \''.line_item::ITEMTYPE_SERVICE.'\'
                GROUP BY order_id) AS e

++++ working correction: ++++
LEFT JOIN
(SELECT order_id, discount FROM
'.cms_db_prefix().'module_orders_items
WHERE item_type = \''.line_item::ITEMTYPE_PRODUCT.'\' OR
item_type = \''.line_item::ITEMTYPE_SERVICE.'\'
                GROUP BY order_id) AS e

Thanks,
Gary