Something I have noticed a lot more of recently especially at resorts is that any advance purchase rates need booking 60 days or before, after that you can only book member rates with 1-14 day cancellation policies. The OTA's still seem to have plenty of Advance Purchase rates for the same resorts but you cannot BRG as no way to make a comparable booking on Marriott.com

Seems maybe the resorts have found a way to offer what they wish to the OTA's and avoid issues of BRG's. Used to be 14-30 day advance purchase was the usual on spg.com. Not sure how it was for Marriott properties, but a definate shift from the SPG ones!