Placeholder showing up in invoices and emails

-- HikaShop version -- : HikaShop Essential: 2.3.5
-- Joomla version -- : 3.4.8
-- PHP version -- : 5.3.29
-- Browser(s) name and version -- : Chrome

The placeholder {id size ="4"}, which is the setting for Order Number Format is being recorded, as is, in the order_number field in the orders table. It is not being replaced by a number, but is showing up in invoices and emails literally. The value for Invoice Number Format is {order_id}.