You can't audit administrative tasks that are related to mailbox moves in Microsoft Exchange Server 2019 or Exchange Server 2016. The New-Moverequest, Resume-Moverequest, and Remove-Moverequest cmdlets aren't logged in Audit logs.
To fix this issue, install one of the following updates:
For Exchange Server 2019, install the Cumulative Update 8 for Exchange Server 2019 or a later cumulative update for Exchange Server 2019.
For Exchange Server 2016, install the Cumulative Update 19 for Exchange Server 2016 or a later cumulative update for Exchange Server 2016.
Learn about the terminology that Microsoft uses to describe software updates.