FYI, you can find some better award availability than the calendar may indicate if you are willing to book a longer stay.
I currently have a 2 night booking there (Mar 22-24) using one paid night and an ambassador free night. I had managed to then separately snag a Chase free night on Mar 22-23 and was then trying to use either points or Player2's Chase free night to get the night of 23-24, and I would then use these instead of my original 2-night booking (which I would cancel).
Could not get the night of the 23-24. However, I would have been able to get a 3 night stay for March 23-26 as an award stay on points, even though those did not show as available on the calendar to me.
Basically, they appear to have the Emerald Overwater Villas vacant on several days but are not letting you book 1-night stays on some of those days (ie. weekends, or potentially days in which the hotel has high vacancy in general). This indirectly blocks the Chase Free Night on those nights since you have to book those individually, but you may still be able to get award stays if you can book a longer timeframe. (In my case, I can't, since I head off to the Conrad on the 24th, but someone else can take advantage hopefully)