The code below allows you to export a Dynamic Distribution group’s members using Powershell. The script itself can be downloaded from this Github link.
Param (
[Parameter(Mandatory=$True)]
[string]$365DynamicDistributionGroupName
)
$dldetails = Get-DynamicDistributionGroup $365DynamicDistributionGroupName
$members = Get-Recipient -RecipientPreviewFilter $dldetails.RecipientFilter -ResultSize unlimited | foreach {$_.Name}
#OUTPUT
echo "=========== ======== ======== ==========="
echo "* DYNAMIC DISTRIBUTION GROUP MEMBERS *"
echo ""
echo $members
echo ""
echo "====== END OF OUTPUT ======"