Shuttle did not transfer a new Etsy listing to Shopify because your Shopify store already has a product with the same SKU. Instead of creating a second copy, Shuttle matched the listing to that product.
Why it happens
This happens when Shuttle transfers new Etsy listings to Shopify automatically. See Automatic Product Transfers between Etsy and Shopify.
Match by SKU is on. When "Match products and variations by SKU" is ticked, Shuttle looks for the listing's SKUs in Shopify before it transfers. You can check this in Settings → Products → General.
One Shopify product already uses that SKU. If exactly one Shopify product has a variant with one of the listing's SKUs, Shuttle treats it as the same product. Search your Shopify products for the SKU to find out which one it is.
How to fix it
If the Shopify product is the same item as the Etsy listing, you don't need to do anything. The two are now matched, and Shuttle keeps them in sync.
If it is a different item:
Give one of the two products a new SKU, so that no other product shares it. If different products in your shops often share SKUs, untick "Match products and variations by SKU" in Settings → Products → General.
In Shuttle, go to Products and find the Etsy listing.
Click the three-dot menu on the listing's row and choose Match to Shopify.
Click the link to un-match, then click Yes, reset match.
Click Transfer to Shopify on the listing's row.
To learn more about how matching works, see Matching Products & Variations.
Still seeing it?
Contact our support team if this message still appears for the listing after you fixed the match, and its SKUs are not used by any other product in either shop.