If an attendee to an occurrence of a recurring series is removed.
Then the series is updated.
The removed attendee is re-invited and the meeting shows back up on their calendar.
The following steps can be followed to reproduce the error.
1. Create a recurring meeting with “Organizer 1” and “Attendee 1” for at least 2 days.
2. Open any occurrence of the meeting and remove “Attendee 1” and send the update
3. Open the series and make any modification(e.g., Add a note to the details) send the update.
You should notice that “Attendee 1” still has the meeting on their calendar, however when you open the occurrence of the meeting that had “Attendee 1” removed, you will notice that “Attendee 1” is not in the meeting.
Chris further adds:
This is not a problem in CDO 1.21 .... This is a problem in Outlook. When a recurring series is updated it does not send the correct updates for the occurrences.This is similar to a problem Microsoft has acknowledged with resources of which we had written earlier:
We've had reports of meeting locations being overwritten to exceptions to
recurring meetings. As Microsoft KB Article 916108 shows, it is an acknowledged bug in Exchange.