Send As permission not working and unsure where to troubleshoot

Hi everyone

I had this functionality working and about a day or so ago it stopped for a distribution group I have.  No Windows Update have been done so I am unsure what the issue is.

Originally I granted the permission using: Add-ADPermission marketing -ExtendedRights Send-As -Userusername -AccessRights ExtendedRight | fl

When I check ADUC, the Send As permission is granted, and running "Get-ADPermission "marketing"| where {$_.ExtendedRights -like "Send-As"} | ft -AutoSize" confirms the same.

Can someone offer me some troubleshooting steps?

Thanks