With the exception of a limited number of blackout dates, every hotel is required to make a percentage of their rooms available for standard awards. Redemptions may be booked 50 weeks in advance. Once that inventory is taken, members may use Anytime Awards for last room availability on standard rooms. If the hotel is selling standard rooms, you should be able to redeem an Anytime Award.
The exact definition of standard may vary from hotel to hotel, but should include the vast majority of rooms at the hotel. Some exceptions would include suites, ocean view, etc. The same restrictions that apply to paid stays would apply to Anytime Awards, including minimum length of stay requirements and/or advance deposits to name a few examples. If the hotel is sold out, clearly you would not be able to redeem standard or anytime awards.
We will also not allow Platinum members to use their 48-hour guarantee benefits from a paid stay and later convert that paid stay to a redemption. Some groups will book meetings more than 50 weeks in advance, which may result in no rooms being available for sale 50 weeks in advance. But again, if the hotel is selling rooms, then you should be able to use Anytime Awards.
The Rome Marriott and JW Capri fully participate in standard awards, but only allocate a limited number of rooms for Anytime Awards. These two locations are the sole exceptions to our policy and we have updated our terms and conditions accordingly.
I have forwarded on the specific examples you have cited and they will be corrected shortly. Regarding the challenges you encountered on marriott.com., the future rate availability function shows availability for any rate programs the hotel has created, regardless of whether those room pools are available over the next 4 weeks. That is why you get the error. These are valid rate programs, but do not have inventory allocated. If they are in violation of the policy as stated above, we will monitor and adjust accordingly.