Hi @GhostWins
I tested in my lab and seemed to reproduce this issue.
Have you updated OAB on Exchange server after you update the seniorityindex?
You may use this command in EMS to force the OAB update:
Get-OfflineAddressBook | Upate-OfflineAddressBook
Once OAB is updated (in Exchange application log you should see Event 17001 followed by Event 17002)
please manually download OAB in Outlook: Send/Receive>Send/Receive Groups>Download Address Book.
And see if it can help with this issue.
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