This discount was released over a month ago, and 30% is considerably better than the general public discounts that have been offered for the past few years, more in line with what AP discounts typically are. So people jumped on it. Availability is really going to vary depending on your dates--just checked for giggles and I am still seeing plenty of availability for that discount on random weeks in July. It could be your dates that are the issue or where you're looking, the biggest percentage savings is almost always going to be the deluxe &
DVC tier ("almost always"--the Poly generally sees smaller discounts, as with this one). And bear in mind with this specific discount the number of days matters. 30% is "5 or more". If your trip is shorter than that it's 25% even in that top tier.
There is no crystal ball here. Just keep checking, sometimes availability opens up because people cancel. Or you may need to adjust your dates.