SqlRS: Must be run as a local administrator when using PSDscRunAsCredential

Details of the scenario you tried and the problem that is occurring:
When running xSQLServerRSConfig. The user set as PSDscRunAsCredential must have permission to run WMI queries.

The DSC configuration that is using the resource (as detailed as possible):

xSQLServerRSConfig 'Integration_Test'
{
    # Instance name for the Reporting Services.
    InstanceName         = $Node.InstanceName

    <#
        Instance for Reporting Services databases.
        Note: This instance is created in a prior integration test.
    #>
    RSSQLServer          = $Node.RSSQLServer
    RSSQLInstanceName    = $Node.RSSQLInstanceName

    PsDscRunAsCredential = $SqlAdministratorCredential   # <--- DID NOT HAVE WMI RIGHTS

    DependsOn            = @(
        '[xSQLServerSetup]InstallReportingServicesInstance'
    )
}

Version of the Operating System, SQL Server and PowerShell the DSC Target Node is running:
Windows Server 2016, SQL Server 2016, WMF 5.1

What module (SqlServer or SQLPS) and which version of the module the DSC Target Node is running:
SQLPS

Version of the DSC module you're using, or 'dev' if you're using current dev branch:
Dev

Start at the xSQLServerRSConfig resource and trace the WMI queries made when PSDscRunAsCredential is used. Determine whether the missing WMI permission should be handled by the resource or documented as a prerequisite, then verify the chosen behavior on the stated Windows Server and SQL Server versions.