Appointments+ [app_monthly_schedule]

We are about to launch Appointments+ for a hair salon (we're already using it for other services). Everything works fine in our testing. However we have just entered all existing June appointments into the system, and the page with the [app_monthly_schedule] shortcode will not load for one of our providers:

* The page will not load for Provider A, who works every day, but will load for other stylists who work 2-3 days a week
* The page will load for all providers in May (only 1 week's appointments entered), July and August (no appointments entered), but will not load for June (all appointments have been entered).
* The page tries to load for a long time, then eventually we see the header, the page title, and nothing else.
* This happens in any browser, on any computer.
* This does not happen in our dev site, which has the same settings but no appointment data.
* If we use [app_schedule] instead of [app_monthly_schedule], the page always loads for all providers.

We suspect that when the month is fully booked, there is too much data for the system to render Provider A's schedule. Have you seen this before? Is there a solution? It seems like a fixable bug, if the calendar is set up to display a month, it should be able to handle a month's worth of data. My client greatly prefers the monthly calendar to the weekly.