Unwanted product in coupon product box?

-- HikaShop version -- : 2.6.0
-- Joomla version -- : 3.4.4.
-- PHP version -- : 5.4.24
-- Browser(s) name and version -- : Firefox

Hi, Please see the attached screen dump. Every-time I create or amend a coupon the same unwanted product keeps appearing the in 'product' box, this prevents the coupon from working correctly, it will delete out but keep coming back every time a change or save is made

Hello,
That's weird, you should not have a product with an ID inferior to 1, can you delete that product and create again so that it won't have an ID equals to 0 ?
Thanks.