Microsoft Bookings now supports online meetings and group services

I have found that if I choose "1 day" for my service duration instead of a number of hours like "8 hours", even though I have maximum attendees set to "20", it only accepts 1 booking.  After that, the day is greyed out, even though on the calendar view of the admin page it says "1 out of 20 seats have been booked".  Is this a bug?  My only workaround is to create 19 more dummy mailboxes and add them as "staff", since it is only allowing 1 booking per staff member.  If I use "8 hours", I can successfully have 20 customers book the same time slot.  I did notice that when you choose "1 day", I get a warning that says "Please note, personal calendar availability will not be accounted for in multi-day services".  I suspect this warning isn't telling the whole story.  My service is only 1 day, not multi-day.  The staff member is just a dummy mailbox that will never have anything on it's personal calendar, so I am not concerned about overlap with a personal event.  Am I missing something?