https://www.bleepingcomputer.com/news/microsoft/microsoft-fixes-outlook-issue-blocking-access-to-emails-calendars/ > Microsoft has addressed a known issue affecting Outlook for Microsoft 365 customers that prevented them from accessing group mailboxes and calendars using the Outlook desktop client. > The buggy Outlook version was released to the Current Channel on March 28, and the fix is rolling out to all impacted users with Outlook Desktop Version 2304 Build 16327.20214.