Bonnet Creek has absolutely nothing available until Nov 27th, as well. They'll tell you tower 6 is under renovation and also how unusually busy they are. I still cry foul - they've taken away all availability.
I saw this happen when I was watching Ocean Walk closely this summer before our family reunion (was able to book a few of our rooms at a discount when some rooms came available and cancel the full point ones booked earlier). The most current 2-3 week span would have rooms here and there, then the whole time frame would be unavailable for several days, then I'd see the rooms come available again. My best guess is if they get nervous about being overbooked or something, they in essence shut down any booking opportunities til they get comfortable things are okay.
I'm guessing something like that is going on right now at Bonnet Creek (we saw this several years back when they had a water main break - but they say no problem at the moment). Maybe something similar in Austin?
Unless someone has some insight to what's really going on, we'll never know and they'll just say how busy things are (and many of them believe it, I think).