Delegate Access to someone else's calendar will not work unless both individuals are migrated and will need to be recreated. If these steps are not taken, previous delegate access should actually resolve after a few days.
Delegate access not working after email migration - both parties have been migrated:
- The Delegator should remove the Delegate in their email client
- Delegator logins into email in a web browser: https://outlook.office.com
- Click on calendar view on the left
- Click on Share towards upper right
- Click Calendar
- In the Enter an email address or contact name box - start typing individual's last name - click on name when search completes
- Name will validate then click drop down on Can view all details and choose appropriate access
None at this time.