There are five enrollment centers in California including SFO. I assume you tried to check and book an interview and all the system came back with was the San Diego-Otay Mesa office. Hard to say exactly what that means but the easy answer was none of the other offices had any interview slots available. I live in San Antonio, Texas and my first try came back with a list of other offices in Texas that had appointments but nothing at SAT. Two hours later after deciding to take a road trip to an office about 150 miles away I logged back in and all of a sudden SAT was visible and had plenty of slots available. Beats me why other than maybe SAT hadn’t updated it’s calendar database that morning or it was offline fir some reason. Keep trying.