Using Classic Outlook on Windows for personal email, calendar, and contact management
My company was plagued with this issue as well. We found out this issue started occurring when we implemented TNEF for voting options within Outlook.
Once this change was reverted any issue related to the calendar was resolved immediately, including:
- Calendar meetings not being removed from attendees calendars.
- Cancellations or modifications sending as HTML and not a calendar item.
- Attendees not being able to remove said meetings from their calendar.
Not sure if it will be the same for everyone else but worth a try!
Hope this can help someone as it's a very frustrating issue.