Glad people have had success! Disney's online and phone systems aren't able to handle surges in volume, of any kind. They have GOT to fix that! The number of times I've waited on hold, had online glitches, etc., all related to surges due to discounts being released, or dining reservation things... it's amazing they can't figure this out.
For all the reservations I tried to make this morning, it looks like only the last one I attempted on each day worked... which is kind of a bummer, as the first several tries I was offered better dining times for my schedule, only to get the error screen and start over again. After several rounds of this, the dining times I was offered were not ideal, but I tried them anyway, then I gave up. Then magically, reservations appeared in MDE. Not complaining, though!! Happy to have anything at all.