For some reason, I can't create periodic bookings via the AJAX interface of PloneBooking 2.2.1. When I try to do that, it would say
"Can't create any periodic." (See screenshot)
However, if I try to create periodic bookings by using the "booking_periodicity_form" page (go to the booking itself and click on the tab "Periodicity"), I can generate the bookings successfully. So, this bug should have something to do with the AJAX interface instead of the underlying logic in the function getPeriodicityInfos in Booking.py.
Periodicity configuration screen of the AJAX interface