eBay doesn't want to try and filter out banned items (such as modern unused postage from Cuba) from allowed items (such as older used stamps), so they just filter on the word 'Cuba'. Some sellers try to get around it by using terms like Greater Antilles, but if they get reported they can suffer the same fate as using the actual country name. Try selling those on HipStamp or Delcampe instead. (Although a few hundred mostly modern issues such as you describe won't have a huge value).
