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You must have the correct supplier product ID on the product
Step 6 - do you have any incorrect barcodes or alternate codes on the product?
If you have the incorrect barcode on the product, it can replace your supplier code on the product with the one that they have matching that barcode. i.e. if you have 2 different barcodes on the product, each one belongs to a different supplier product id, this can cause the product to replace the correct supplier product ID against that supplier to a different one matching the secondary barcode. Remove the incorrect barcode and put the correct supplier product id against the supplier. This should fix this issue moving forward.
NOTE: my understanding is that the RS3 feed will NOT create new products and if that supplier is not on the product then it will not update the product with that supplier information unless it can match other criteria for that supplier on the product.
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