Attendees disappear from meeting invite in Outlook

A few days ago I got a question from an end user that reported quite a strange issue regarding Meeting invites in Outlook.
The user added a meeting room to the meeting invite, and then when the user added a distribution group to the invite, the meeting room and the group disappeared and no meeting was sent or created.

After a bit of troubleshooting on the client, I couldn’t find any issues with her Outlook client. This lead me to dig a bit deeper into the Troubleshooting with the help of Powershell.


The first thing I did was to connect to the Exchange Online Powershell Module.
After that I saved all the members of the distribution list to a variable so I can later use it for a Foreach loop.
After comparing a variety of attributes for the members, I ran the command below and got some interesting information.

As you can see on the warning above, one of the users (ErrorUser) are “corrupt” and this is because of incorrect ”WorkingHours” which Microsoft doesn’t support.

The solution to the issue was to change the ”WorkingHoursStartTime” and ”WorkingHoursEndTime” values so they matched the other users in the distribution group.

After I did that change I contacted the end user who reported the issue, whom then verified that they could now send the invite as usual.

If you have any questions regarding this don’t hesitate to contact med at or by leaving a comment below.

Disclaimer: All information on this blog is offered "as is" with no warranty. It is strongly recommended that you verify all information and validate all scripts in isolated test environments before using them in production environments.