Can't search any results in manually added shared mailbox in Outlook in Exchange Server 2019 and 2016

Symptoms

In a Microsoft Exchange Server 2019 or Exchange Server 2016 environment, assume that you manually add a shared mailbox as an additional account for your primary mailbox in Outlook 2019 or Outlook 2016. You may only get the search results from the primary mailbox and no search results are returned from the shared mailbox. 

Resolution

To fix this issue, updates for both Exchange Server and Outlook are needed.

For Exchange Server, install one of the following updates:

• The Cumulative Update 2 for Exchange Server 2019 or a later cumulative update for Exchange Server 2019.

• The Cumulative Update 13 for Exchange Server 2016 or a later cumulative update for Exchange Server 2016.

For Outlook:

• For Outlook 2019, install the latest update.

• For Outlook 2016, upgrade to Outlook 2019 and install the latest update.

References

Learn about the terminology that Microsoft uses to describe software updates.