Assume that you're in a co-existence environment with both Microsoft Exchange Server 2016 and Microsoft Exchange Server 2013, and the arbitration mailboxes are moved to Exchange Server 2016. When you use Exchange Management Shell to do an eDiscovery search against Exchange Server 2013 mailboxes, the search result fails, and you receive the following error message:
Response from the EWS endpoint 'https://mail.contoso.com:444/ews/exchange.asmx' contained invalid preview results. Invalid value was returned for sort value in one of the preview items.
This issue occurs because sort orders of Exchange Server 2016 aren't working correctly for Exchange Server 2013 mailboxes when arbitration mailboxes are located in Exchange Server 2016.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.