Exchange 2016 - need help listing members of Dynamic Distribution group

The results from the following command is not accurate.  It simply lists all mailboxes on the server.

$test = Get-DynamicDistributionGroup groupname
Get-Recipient -RecipientPreviewFilter $test.RecipientFilter | sort name

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The properties of the group are:

RecipientContainer                     : (OU with limited users in it)
RecipientFilter                        : ((RecipientType -eq 'UserMailbox') -and (-not(Name -like 'SystemMailbox{*'))
                                         -and (-not(Name -like 'CAS_{*')) -and (-not(RecipientTypeDetailsValue -eq
                                         'MailboxPlan')) -and (-not(RecipientTypeDetailsValue -eq 'DiscoveryMailbox'))
                                         -and (-not(RecipientTypeDetailsValue -eq 'PublicFolderMailbox')) -and
                                         (-not(RecipientTypeDetailsValue -eq 'ArbitrationMailbox')) -and
                                         (-not(RecipientTypeDetailsValue -eq 'AuditLogMailbox')))
LdapRecipientFilter                    : (&(!(!(objectClass=user)))(objectCategory=person)(mailNickname=*)(msExchHomeSe
                                         rverName=*)(!(name=SystemMailbox{*))(!(name=CAS_{*))(!(msExchRecipientTypeDeta
                                         ils=16777216))(!(msExchRecipientTypeDetails=536870912))(!(msExchRecipientTypeD
                                         etails=68719476736))(!(msExchRecipientTypeDetails=8388608))(!(msExchRecipientT
                                         ypeDetails=4398046511104)))

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So far I have deleted the Distribution group and created it in ECP with no change (Exchange 2016 now supports creating these within ECP so decided to try that).

At least one user in the correct OU reports not having received a recent email.  The multi-mailbox search shows he received it but wanted to check the group membership and find that I cannot.

I am looking for help getting the correct list of users for the group.

Thank you.