In my 15 years of AP stays, I can't say there's ever been a time a resort was "excluded" per se. However, some resorts have fewer rooms/views/styles available at an AP rate and these vary by night, too. The resorts with which I've found limited availability have been:
Wilderness Lodge
Polynesian
For those, you really need to book as soon as the AP rates are released, especially for busier times of the year. I've almost always found availability - even as close as a week before arrival - at these:
All Stars
CBR
CSR
BWI
AKL