I am in the beginning phase of a hybrid migration from Exchange 2007 to Office 365 using two 2013 servers for the hybrid role. We have two Exchange 2007 servers in two separate sites. Both of the 2013 servers are in Site A, if it makes any difference.
I have migrated 15 mailboxes from on premise to O365. After doing so, the migrated end users are noticing that they are having to re-share their calendar, as people who could previously see detail now are only able to see "Busy". Also, they are noticing that they cannot see on-premise calendar detail until after the on-premise individual has re-shared their calendar with the O365 user.
So, the first question - is this to be expected, or is there a way to circumvent this prior to the mailbox being migrated?
Additionally, on-premise users who had access to a migrated user's mailbox prior to the migration, are being prompted for credentials in order to access the calendar of the migrated user. again, is this to be expected, or is there some way to mitigate this? Is this where the Online Services Sign-in Assistant comes into play?