[Appointments+] Scheduling issue with Appointments+

I'm trying to setup Appointments+ for a sole proprietor, in other words a single service provider. She is a massage therapist who offers her services in either 50 min or 80 min blocks. There didn't seem to be a way to have 2 options for duration so I created a separate service for each time variant ie. "Massage Therapy – 50 Min" with the 50 min duration and "Massage Therapy – 80 Min" with the 80 min duration.

Here is an example of a problem I am having: A visitor would like to schedule an 80 min session startng at 4:00 PM. When they select the 80 minute service, the calendar that gets generated doesn't allow for starting an appointment at 4:00 (even when the whole day is open). In order to get the possibility of a 4:00 start time, they would only be able to schedule the 50 minute session. Perhaps I have setup the the services incorectly. Is there a way that any time could be a start time as long as there is enough time for the session including padding requirements? You can see what I am talking about by going to https://julieglassco.com/about