It's very strange-a fair number of my listings were hidden, even from me. I had to go on google to find the listings, click on edit and save them, and they eventually reappeared in my closet. They weren't all old listings, and I've always responded to those pop-ups asking to confirm that an item is still for sale. I can tell that other seller's listings are hidden too. From me anyways.Maybe the older ones are falling off because Tradesy doesn't want to store all that information?
I can only see about 2/3 of my own when I'm signed in to my account.

(I mean the items for sale, not the sold items)