Unable to update pre-migration meeting requests after migration to Office 365

We recently migrated from Exchange 2010 to Office 365.  At the same time, we changed our naming structure from last name, first name to first name, last name.

The naming change may have been more significant than the migration to 365.  

My problem is this:  I have staff who have meeting requests with internal and external people from before migration to 365.  While the meeting requests migrated successfully, the meeting owner's ability to edit or change the meeting has been lost.  Even though the account owner's email address is the same, the name order change may have severed the relationship to the object.

When the person tries to update a meeting, he gets the following NDR:
 
            Your message did not reach some or all of the intended recipients.
 
                  Subject:      In-Person Meeting
                  Sent: 8/15/2016 3:36 PM
 
The following recipient(s) cannot be reached:
 
      Person01 on 8/15/2016 3:36 PM
            This message could not be sent. Try sending the message again later, or contact your network administrator. You do not have the permission to send the message on behalf of the specified user. Error is [0x80070005-0x0004dc-0x000524].
 
      Person02 on 8/15/2016 3:36 PM
            This message could not be sent. Try sending the message again later, or contact your network administrator. You do not have the permission to send the message on behalf of the specified user. Error is [0x80070005-0x0004dc-0x000524].

The NDR is implying that the very person who sent the original meeting request no longer has permission to update his meeting request.  I attribute this to both the name order change and the migration from 2010 to 365.  

I'd appreciate any suggestions for this issue.