When you go to import, make sure to sync (this should automatically happen when you visit the import screen). You can also sync by clicking the sync button.
Also, make sure that you have unselected the default “Not Imported” tab to view all of your inventory:
Please note that you can only import active, available listings at this time. Learn more about importing here.
If you are unable to view your entire eBay or Etsy inventory, contact customer support for further assistance.