Deleting old system name-server IPs and adding new ones doesn't actually update the IPs in /etc/powerdns/recursor.conf when using system nameservers.
Steps to reproduce:
configure set service dns forwarding system commit delete system name-server set system name-server <new ip> commit cat /etc/powerdns/recursor.conf (still shows old name-server IPs) run restart dns forwarding cat /etc/powerdns/recursor.conf (still shows old name-server IPs)