Exchange Mailbox Migration Errors - Corrupted items

It looks like for the most part these are ACL errors, most likely meaning that the user who has the permissions to the folder/item/mailbox in on-prem Exchange is not present in EXO. Generally this is safe to ignore.

There is one corrupt item in the list ("Model walkthrough with NT"). This won't be migrated and will need to be manually re-created in the EXO mailbox, unless you can fix the error (i'd say it's a very old meeting where the start date has been lost because it was so long ago)