Urgh, just all such a mess. Which all goes back to what I was saying, a cancelled reservation that is totally unrelated, but backed up to your desired reservation dates, can result in what you want opening up. It's one of those "law (or in this case, rule) of unintended consequences". I'm sure they never thought that all these silly exceptions to bookings would actually prevent them from selling other stays so in the long run only stand to hurt them rather than save them anything.A room night that is not bookable as part of a longer stay. It may be 1 room night or 2 room nights during a week that are not continuous during the week. Disney's reservation system has a bias built into to prefer a Sunday - Saturday stays.
The system does not like reservations that leave out Friday or Saturday nights. The system also does also not like mid-week booking like Tue-Wed-Thru.
Once you get to the 5 day window 1 and 2 days options tend to pop up.
Dave