Calendar events disappering on new Outlook

Not resolved!

• calendar invites spontaneously disappear
• If sender reschedules invite, whole series disappears
• New calendar invites are not consistently on calendar after accepting
• Cannot search emails
• Emails not consistently labeled as replied to or forwarded
• New Outlook for Mac is NOT READY FOR LAUNCH

Had to move back to Legacy and hope Microsoft will continue to support until new Outlook is functional

Dear dan.

Based on my research, I'm not currently aware of any widespread or known issue causing calendar events to spontaneously disappear specifically in the New Outlook for Mac. While isolated cases can occur due to synchronization issues, account configuration, shared calendar behavior, or client-side problems, I haven't found any recent Microsoft service advisories or broadly reported incidents matching this scenario.

Please sign in to your calendar in Outlook on the web first, and check whether the missing events are still available there. Also, expand all calendar groups in Outlook and make sure the correct calendar is selected.

If the events are missing online as well, please check the Deleted Items and Recover Deleted Items sections for any calendar appointments that can be restored.

Moreover, to help narrow down the cause, could you provide a few more details?

• Are you using a Microsoft 365 work/school account, a personal account (@hotmail.com/@outlook.com), or Exchange Server?
• Are the missing events from your primary calendar, a shared calendar, or a delegated calendar?
• Do the events also disappear in Outlook on the web, or only in New Outlook for Mac?
• Is this affecting only your mailbox or multiple users?
• Do you notice the events being deleted, moved to another calendar, or simply no longer displayed?
• What version of Outlook for Mac and macOS are you using?
• What version of Outlook for Mac and macOS are you currently using?

In the meantime, below are some steps that you could try: 

Step 1. Check if the missing data is truly gone or just not displaying

Open Outlook for Mac, go to Preferences > General > Turn off “New Outlook” (if you’re using New Outlook, switch back to Legacy Outlook). Some users report that recurring series data may not render correctly in the new interface. See if the details reappear in Legacy Outlook view. 

Try expanding a recurring series into a single occurrence (open one instance and check “This Event Only”). Sometimes the details are still in the backend but not shown on the series container.   

Make sure that you're viewing the correct calendar and that no filters are enabled: Outlook > View > Reset View > Verify the calendar is selected in the navigation pane.

Step 2. Check for a local backup of the Calendar Database

Outlook for Mac stores local calendar data (especially “On My Computer” items) in a database. When macOS updates, sometimes this database can be affected. Here’s how to check for previous versions:

• Close Outlook completely > Open Finder, then go to: ~/Library/Group Containers/UBF8T346G9.Office/Outlook/Outlook 15 Profiles/Main Profile/Data/  
• Look for files like Outlook.sqlite or Calendar.sqlite.
• Check if there are any backup copies, or use Time Machine, if enabled, to restore a version from before the OS update. (Note: If Time Machine is enabled on your Mac, this is the best chance to recover the lost data.)

Step 3. Export what you still have

In Outlook, go to File > Export > choose Calendar > save as an .olm file. This ensures you have a backup of the current calendar before you attempt recovery steps, so nothing gets overwritten.   

Step 4. Try creating a new Outlook profile

Quit Outlook, then open Outlook Profile Manager (search Spotlight for “Outlook Profile Manager”). Create a New Profile and re-add your account. If the calendar data is truly local, you may need to import the .olm backup into the new profile to check if the series data restores correctly.

For more information, you can refer to this case: How to recover Outlook calendar event data missing following Sequoia OS update on a MacBook Pro

Note: As this is a public community forum, please understand that I don't have access to your mailbox data or service logs to determine whether this is a display/sync issue in Outlook for Mac or whether the events are being removed from the mailbox itself.

Thank you for your patience and understanding. If you have any questions, please feel free to reach out. I'm looking forward to your update