I'm working with an instructor and she said that her appointments in the Canvas calendar are automatically canceling for some unknown reason.  She is using the standard calendar process of Course Calendar > Create New Event > Appointment Group.  It's unclear if this is affecting all of the calendar items or just some.  Her students will get a cancelation notice, but she doesn't.  I've looked at all of the settings, and everything looks fine.  If it matters, it's a Supplemental course that is 3 years old (this is the first time they've used the calendar function).