Dollar not offered for September 18?

We hired an intermediate SUV (as we usually do)for our Florida trip last month (May 18) and chose Dollar as they were the cheapest by far between Alamo and Dollar this time.
Just been checking on US Car Hire site for possible visit in September '18 and Dollar is not quoted for any class of car. Only quotes are from Alamo and National ??? Curious to know why no Dollar alternative.

Can you confirm if you entered a referrer code? Dollar and Thrifty only show when a code is entered. Unless you use the phone app then will always show.