Newly created subdomain sub.example.com can not be resolved despite the fact that its record exists in
# grep sub.example.com /var/named/chroot/var/
sub.example.com. IN A 203.0.113.2
# dig +short sub.example.com @127.0.0.1
DNS zone for example.com is signed by DNSSEC.
Select Unsign and sign DNS zone again for example.com: Plesk > Domains > example.com > DNSSEC