DNSSEC is enabled on our domains but result.isAuthenticData() always returns false

We've enabled DNSSEC via Route 53 on two of our domains.
One is the parent domain "parent.com", the other is a subdomain "child.parent.com".

isAuthenticData() fails for both of these domains because both SRV records point to "service.parent.com" and "service.child.parent.com" respectively.

Online DNSSEC tests validate both of the service domains but minidns does not seem to.