Why would my clients not be able to schedule or reschedule in my calendar, even if I have available times?

In a situation like this, you need to check a few things:

1. When your clients access your calendar, are they scheduling a date/time that falls within one of the blocks of time marked with "Available"? Remember that if a client tries to schedule an appointment that falls outside of the available block of time, they will not be able to do so.
2. When your clients are rescheduling an existing appointment, are they doing with more than 24 hours in advance of said appointment?  There is a "lockout" on your calendar and clients/prospects are not able to reschedule appointments (even when there is a block of time marked "available") if they try this with less than 24 hours in advance. This is to ensure that you don't have any surprises in your schedule and can maintain good time management. And in such a case the clients need to contact you directly and tell you of their change of plans.

If the above two conditions have been met, then please submit a support ticket in the Help Desk (from your coach dashboard > section "Support") where you provide examples of your clients (names) who are attempting to schedule unsuccessfully an appointment on your calendar and let us  know the date and start/stop time they attempted to schedule their appointment for. We can then dig further to see what is causing this.