I tried to book for two on 10/27 and it wouldn't let me, however I could book for three. I just called and the CM did not find anything for two either, and had said that earlier today they were having issues booking for two and it evidently hadn't been fixed yet. She booked me for three and then immediately refunded one. Roundabout way of doing it, but at least it's done!
Thank you for this hint. i called earlier and was told my date (10/25) was sold out, and it also showed as unavailable when i looked online. after reading this, i called back, and the CM still could not book for 2, but was able to book for 3 and then cancel 1. objectively i know i shouldn't be so happy about spending $140 on desserts, but we always enjoy the parties.
now i've just got to decide if i cancel my illuminations dessert party for the next day, or if we make this a full-on dessert assault of a vacation.