Appointments+ is not blocking time for the appointments created in Google calendar

I’ve installed Appts+ and set up two tax preparers that are able to be booked online.
They each have a separate google calendar. I created a google calendar for appts+ and synced their calendars to it. Google calendar is populated their schedule on the calendar, so the google calendar is connected to appt+, BUT it is not blocking the times on appts+ that are not available on Google.

I just want to be able to book two time slots on appt+, 1 for each tax preparer, and if one or both of them are already booked on Google to have that time blocked out on appt+ booking calendar.
Right now, it is not blocking times off on appointments that should not be available.