Prevent Add-On items from being uploaded
There is a new setting in your Account > Settings > Marketplace Settings > eBay (then Amazon sub tab) ... click here to go directly there.
If this setting is set to Yes, then Amazon items that you try to upload will be flagged and a warning triangle will appear in the Bulk Upload report:
You can still opt to ignore the warnings, even if you have the main "Do not upload add-on items" turned on. To ignore the warning and still upload the add-on items, then use these options in the drop down menu on the bulk upload report: