"Add to Calendar" functionality in the New Outlook

Hii, zivrivkis​, I don't think you're doing anything wrong here. Since you've been able to reproduce the same behavior across different accounts and devices, it seems less likely to be something specific to your setup.

Based on what you've described, this may be related to how New Outlook is currently handling the Add to Calendar action. If the event appears briefly and then disappears, it might not be completing the save process correctly.

Since opening the attachment and selecting "+ Add to Calendar" works consistently, I would probably use that as a temporary workaround for now.

One thing I would also check is whether the event appears in Outlook on the web after using Add to Calendar. If it doesn't show up there either, that would suggest the issue isn't limited to the desktop app.