Symptoms
In Microsoft Exchange Server 2019 or Exchange Server 2016, when you run a command like set-mailbox with necessary switches together with the switch -Whatif:$False, the auditing is skipped for this set-mailbox command execution.
Resolution
To fix this issue, install one of the following updates:
For Exchange Server 2019, install the Cumulative Update 2 for Exchange Server 2019 or a later cumulative update for Exchange Server 2019.
For Exchange Server 2016, install the Cumulative Update 13 for Exchange Server 2016 or a later cumulative update for Exchange Server 2016.
References
Learn about the terminology that Microsoft uses to describe software updates.