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If you share delegate access to your local Exchange account with others or vice versa, the shared calendar or mailbox may disappear from view and you'll need to supply/be given that access a second time. If you share calendars with others, they will appear as disconnected and may give you errors until those accounts are migrated to O365. Right-click on a calendar and remove it from your view, then re-add it once it has been migrated.
A common example calendar that will need to be reconfigured is "KI: HQ Staff Calendar" or "ki-hq-staff-calendar-res@mit.edu". For instructions on how to do soreconnect this calendar as well as others in Outlook, please see below:
Adding Shared Calendars:
https://it.cornell.edu/applecal/view-shared-office-365-calendars-apple-calendar
Sharing Calendars/Providing Delegate access:
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