You can’t expand and display Dynamic Exchange Distribution Group members in Outlook like you can with a normal Distribution Group.

The quick and easy Exchange PowerShell command to display Dynamic Distribution Group membership:

• Get-Recipient -RecipientPreviewFilter (Get-DynamicDistributionGroup “Group Name”).RecipientFilter

Unfortunately, if your Distribution Group utilizes Recipient Container parameter, the above command will not work properly as it doesn’t respect Recipient Container and will display all recipients, regardless of their Organizational Unit.

To get around the issue, use the following command instead:

• $GroupName = “Group Name”; Get-DynamicDistributionGroup $GroupName | ForEach {Get-Recipient -RecipientPreviewFilter $_.RecipientFilter -OrganizationalUnit $_.RecipientContainer} | Select DisplayName,PrimarySMTPAddress, OrganizationalUnit | Sort-Object -Property DisplayName

Microsoft Exchange 2016
Windows Server 2016