Dynamic Distribution Group User Count

When I run this command on the exchange server and get a user count it is including more users than we should based on the filters.

Set-DynamicDistributionGroup -Identity Accounting@xyz.com -RecipientFilter {(CustomAttribute13 -eq "Accounting") -or (CustomAttribute13 -eq "Accounts Payable") -or (CustomAttribute13 -eq "Accounts Receivable") -or (CustomAttribute13 -eq "AP")}

When I run the following command I get a user count that exceeds what it should be:

# Count members of the distrogroup
$members = Get-DynamicDistributionGroup -Identity “Accounting”
(Get-Recipient -RecipientPreviewFilter $members.RecipientFilter -resultsize unlimited).count

The total user count is around 58000 users instead of around 30000 users. I have exported the user count to a csv file and I can see users included on the list that do not have CustomAttribute13 set to any of the values that I specified.

Any ideas?

ExchangeGuru