I'm taking the day flight IAD-LHR on Sunday. This flight has been F0 and C0 for weeks, so I have long ago given up hope of my upgrade clearing, but I have checked it on Expertflyer now and then (more to investigate the chances of a bump than out of any real hope of a bunch of paid C passengers canceling). Last time I checked, all the seats in the F and C cabins were assigned as you might expect. But this morning, these seat maps are showing as unavailable. The Y map is showing, but with only 7 open seats although the class availability being Y9 B9 M9 H6 Q4 V3 W2 (obviously no great mystery given that they'd be expecting a few no-shows, assuming that all confirmed passengers have been assigned seats whether they've requested them or not). But what's with the vanishing premium class seat maps - I've never ever seen that happen until a few hours before departure before.