Cancellation points took about 8 hours to post.
I tried to make the desired reservation via the app and of course, it showed no availability. Last night, when I proposed this exact scenario to the Diamond Desk agent, she said "Oh I expect no issues. I can see 15 rooms available for points in that specific room type."
I called in to the Diamond Desk and they echoed the results shown online. Mysteriously, all 15 of the 2Q rooms described as available 8 hours were showing as unavailable.
She was able to "force" (her term, not mine) into an accessible room at the standard room award rate.