I feel it doesn't clear itself you may have to reinstall the game. at one stage I had a similar, though not exactly th same problem. In the end I reinstalled, very nervous about whether I would lose all my upgrades. Worked perfectly, got all my upgrades back once I connected with Facebook and now works fine.
I'm with you broilmebk, no one can actually buy them, so: Why would anyone do it? and How come the slots aren't filling up with these large sales as noone can buy them? My theory is that most of the ingredients for sale aren't from real players but put there by the game to feed real players the ingredients we need to play…