When target migrated users are using their switched mailbox and when they click on "Send/Receive" then an error is displayed in "Errors" tab of "Outlook Send/Receive Progress" window:
"Task 'Microsoft Exchange Server' reported error (0x8004010F) : 'The operation failed. An object could not be found."
This is a known issue and is mentioned in the Release Notes for EMWProf:
Please follow the instructions from EMWProf Release Notes (mentioned above), publish the version 2 of the OAB and force a rebuild of the OAB.