Weird... I booked my 180+10 on Sunday... online... with no issues.
I had booked my resort stay earlier in April, online, through Disneyworld.com, logged into our MDE account.
On Sunday, my 180 day mark, I logged into MDE via our Desktop and was prompted with the options of "reserving" FastPass+, Dinning, creating an Itinerary, etc... I chose Dinning reservations, directly through our MDE "home page" and was re-directed to the standard ADR page.
When I moved the calendar to October, all dates of our vacation, including departure, were available for search/booking.
Even at 7:45a... I was able to book BOG for 5:55p the night of our intended MNSSHP. No phone calls were needed... Credit Card information was entered once and stored for ease of making multiple reservations.