A single user was experiencing a situation where after sending a recurring appointment and then later editing that appointment to set a new time, all or most of the appointments would be removed from the calendar. The other recipients would see the updates.
This would only happen if the appointment was opened and edited. It would not happen if the appointment was clicked and dragged to a new time slot.
The user had an entry for themselves in their frequent contacts address book that referred to an old post office that they were previously a member of and had not been updated after a move to a new post office. After removing the entry from the frequent contacts, the edits began to function properly.
The address when editing was taking on the information for the user in the old post office. The edits took on a pending status that would never be corrected.