I was able to download all of your active listings successfully (at least I think). it was a total count to 146. I could not find the listing in question. Are you downloading more than the active listings ( on the main screen you can download inactive and sold listings). The program will always download the active listings first when requested. Listings other than "active" require you to give Zetsy authorization to retrieve these. Have you done this its through Tools : Give authorization on the menu.? The good news / bad news with a desktop application like Zetsy is that NO ONE other than you can download and see this information. It makes troubleshooting more challenging for me but give an better security for all. My advice is to make sure only active listings are checked now and see if that works. If it does, add back the other checks and lets see what happens, Make sure when that in the lower left hand corner you see a key symbol and the words Priv Access.
Under Tools : Check Zetsy Operations is a program self check whcih runs through a bunch of basic stuff to make sure everything is working. You should get no errors when this is ran.
It also could have been an Etsy glitch which has corrected itself. let me know what happens.