PowerDNS servers contain DNS records even though they are disabled in OA and OA reports that the domain is in sync.
The incative DNS records might appear on the PowerDNS server after switching the domain DNS hosting to External and back to Internal.
This behavior caused by software related issue #POA-107283.
This issue will be resolved in one of the future product update. Contact your Technical Account Manager or Pooled Technical Associate Team (firstname.lastname@example.org) in order to trace the current status of #POA-107283.