The problem you experienced today is the same with 13 months out also. The system doesn't work.
and a follow up question....is the online booking restricted to the same phone booking time window 9:00 am to whatever time?
*Note as with the MVCI Weeks system, available DC Points inventory is officially released at 9:00AM Eastern Standard Time on the Release Day. However, several TUGgers have reported that when using the owners.marriottvacationclub.com DC Points online booking tool, they have occasionally seen and been able to book intervals earlier, shortly after midnight on the Release Day. It is recommended that you check for the possibility.
When booking Weeks, yes, the same 9AM Eastern opening time applies to both the phone and online queues.