You may be in a situation where you have a valid UPC or ASIN but limited data. You can still add product data and images based on the ASIN. Please note that the ASIN must already exist and be active on Amazon.
While in the SKU you want to edit, select the Advanced Options under the Amazon card.
Select the 'IMPORT DATA' button
Once the process is done syncing (should take a few seconds) you will see images, titles, brand and more information auto-populated in the SKU!
*NOTE: You still need to add your own pricing information and select the most appropriate SMART Type or Amazon Item Type & Department if you did not fill this information in previously.