Appointments - Working Hours Start Time Ignored?

In settings, I have working hours set to start at 9:30am. My time base is 45 minutes. When I try to set an appointment on my website, I get a greyed out option for 9:00am and a first available appointment of 9:45, followed by 10:30, etc. What I had expected was a first available time of 9:30, next 10:15, etc. Help?