Hi @Wötzel, Michael ,
Welcome to out forum!
In order to beeter understand your issue, please provide some detailed information:
- How are meeting request sent(from Outlook or other calendar tools)? Is there anything special about this meeting(such as it's a recurring meeting)?
And if re-creating a normal meeting in Outlook, could this issue be reproduced?- Who is the organizer of the meeting? did the organizer of meeting is the shared mailbox?
If you are using the shared mailbox, every user that has appropriate permissions could create and cancel the meeting in the shared mailbox calendar, in order to avoid the influence of other users, it's suggested to temporarily delete other users' peimission in this shared mailbox and only retain the permission of one user to test if the issue has any difference. - If the issue still exists, in order to avoid the interference of add-ins, it's suggested to run your Outlook in safe mode and recreate the meeting to check(windows+R>type "Outlook.exe /safe">enter).
- Who is the organizer of the meeting? did the organizer of meeting is the shared mailbox?
If your issue has any update, please feel free to post back, and I would continue to research it with you.
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