Using Purview to audit a shared mailbox

Permissions:

Ensure you have the Audit Logs role in Microsoft Purview. This is part of the Compliance Administrator or Global Reader role, among others.
You may need specific permissions like View-Only Audit Logs or Audit Logs to search and access audit logs within Purview.
Audit Configuration:

Audit Logging must be enabled in Microsoft Purview. This is usually enabled by default, but it’s worth double-checking. You can verify this in the Microsoft 365 compliance center under Audit > Audit log search.
Purview Search Configuration:

When using the Audit interface in Purview:
Activities: Choose "Mailbox activities" to filter for mailbox-related actions.
Users: Specify the shared mailbox in the search field.
Date Range: Set the exact start and end dates to match those used in your PowerShell script.
Results: If you're still not seeing results, ensure the time zone settings in Purview match those used in your PowerShell command to avoid discrepancies.
Time Delay:

Note that there can be a delay in when events are available in Purview. It might take some time for events to be indexed and searchable in Purview, especially if the actions were very recent.