I have made Jeff Hammelman's various ciabatta loaves and they're wonderful. However, with the last batch in particular, having used inverted baking pans for the final proof before putting them in the oven, they've stuck to the pans. I've put sifted bread flour on the pans but they still stuck. I've also used cornmeal in the past but there have still been issues with sticking. Any ideas as to how I can address this? Thanks!