At times, you may get an error when you try to list a product in AccelerList (e.g. client-side error). This may indicate that Amazon's API has insufficient data on the product you are trying to list. As a workaround, you may list the product directly in Seller Central.
For the listed product in Seller Central to be included in the batch, do submit feed instead of previewing and accepting a Shipment plan: (Note: You can list the rest of the products in AccelerList)
Then, create a shipment plan in Seller Central including this product listed directly on Seller Central: