How to change the appointment interval?

Hi there.

I just upgraded to A+ 1.3. Suddenly, the time interval at which appointments can be booked has changed to hourly instead of half-hourly. That is, people used to be able to book at 1:00, 1:30, 2:00, etc. but now they can only book at 1:00, 2:00, 3:00 ,etc. My time base is set to 30 minutes and all of my services are 60 minutes long. How do I fix this?