Problem:
Orders are downloading into Linnworks with one or more items showing as not linked, however the item is already mapped to the Channel SKU. 
When checking the item in Settings > Channel Integrations > Mapping for the relevant channel, the SKU appears to be linked correctly. There is no obvious reason from the Channel Mapping screen alone why the order item should be unlinked.

There are three common causes:

1. The item was archived at the time the order downloaded

If a stock item is archived in Linnworks, any existing mapping between it and its channel listings is removed, even though the listing itself stays active on the channel. Any order that downloads for that SKU while the item is archived will come in unlinked, because Linnworks has nothing to match it to at that point. This still applies even if the item is later unarchived — unarchiving restores the item, but does not automatically relink orders that already downloaded while it was archived.

Solution:

Unarchive the item if it should remain active, then re-download or manually relink the affected orders. Unarchiving alone will not relink orders that already downloaded while the item was archived.

2. The order's Subsource does not match the Subsource the item is linked to

Linking is specific to a Source and Subsource combination, not just the Source. If an account has several similarly named Subsources for the same channel (for example two Shopify Subsources such as "Shopify" and "Shopify UK"), an item can be linked under one Subsource while the order downloads under a different one. 

Soltuion:

Open the item's Product Details > Channel SKU tab and check whether a link exists for the exact Source/Subsource pair the order downloaded under — not just for the channel in general. If it's missing, either relink the item under the correct Subsource, or, if the Subsource is a duplicate/legacy entry, correct the channel's Subsource configuration to prevent the mismatch going forward. Use the Stock Item Linking import to add the missing Source/Subsource link in bulk if this affects multiple SKUs.

3. The linking was not set up using the field the channel requires

Some channel integrations don't link items using the Channel SKU alone — they require a specific channel reference/ID field (for example a listing ID, variant ID, or item ID, depending on the channel) to be used for the linking to be completed correctly. This may cause the order to download with a Channel Refernce field that Linnworks will not be able to recognise as it won't be present in the item mapping. 

Solution:

Confirm which field the channel in question requires for linking (check the Product Details Channel SKU tab for any empty fields and compare to a correctly-linked item on the same channel to see which reference field is populated). If an incorrect link already exists, remove it first using the Delete Stock Item Linking import, then relink using the field the channel requires.

Once relinked, existing affected orders will not update automatically. Relink the orders manually inside of the Open Orders screen or re-download them so the new link is picked up and the order can be processed correctly.

If none of the above match your specific case, please reach out to our support team with an example order & SKU.