I have noticed a slight pattern on eBay. When I have x amount of items sold but waiting for tracking info, I don't do much selling. After I add tracking information for many of these items, I'll make more sales. This got me thinking, so I logged onto my VPS and did a search for a few of my items on eBay on there word for word. None of them came up. And yes I am in a time frame where I have x amount of products waiting for tracking information. Does eBay make your auctions invisible at times until you supply tracking information for products you've already sold? It's interesting for sure.