Apologies - I tried to go through the ticket system to get this bug fixed - but dealing with technical support is like trying to shout through a wall.  

Besides taking a full 24 hours to get a response - I got back an entirely wrong answer.  I hope that a developer reads this and sees that there was obviously a mistake made in implementation and fixes this ASAP.

Here's the bug:

There are three fields for order imports/exports besides quantity and title that are related to the line item on the order: SKU, Channel SKU and Item Number.

Item Number is related to SKU - but it is not SKU: rather it is a unique identifier.  The purpose of this is so that you can send the channel back two tracking numbers for one order and specify which item correlates to which tracking number.  The linnworks documentation supports that it is intended to be such a unique identifier: http://www.linnworks.com/support/settings/import-and-export-data/import-data/import-types/order-import

The implementation is presently incorrect at minimum on the export:

Item Number appears to support correct mapping and importing - but when I try to export the processed order Linnworks exports the item's SKU instead of the unique identifier I imported.

Of course it's possible I'm doing something wrong - but the answer I got from Technical Support was:

"Please note that within the Open Order import routine there are two columns available for item number/sku allocation. The Channel Sku column is used to pick up the custom label value and item unique identifiers from the channels. The Item Number column is referring to your linnworks skus, it can only retrieve your stock item skus and not listing ids. "

Regardless of whether I'm doing something wrong or not - that answer from technical support is most certainly incorrect.

I'd appreciate a response ASAP - because presently every time I have a multi-item order for a certain channel I use the tracking is not exported.  Also - it'd be nice if some customers (or maybe all customers) - had a way to send something directly to a developer.  It appears that in many cases long time customers know Linnworks better than your technical support personnel.

On top of this there is a 'tested' sample shown in the documentation which proves what I'm saying is correct.  Unfortunately I can't get technical support to do anything but insist that Item Number in regards to Order Import/Export is the same as Inventory SKU.

Dmitry,

Not only was it a bug - but a temporary fix has been provided and the permanent fix will be in an upcoming hot-fix.  Please talk to your developers!  It was correctly importing as designed - but the export was the SKU field instead of the Item Number field.  Your online/website documentation is correct - but apparently your internal document is wrong.

Thanks-