I believe you’re missing DNS peering - which forwards DNS queries for the specified namespace originating in the producer network (Apigee X VPC) to the consumer network to be resolved.
I was read about this before post here, but I was make this configuration in a Shared VPC, so my service project (apigee and others) doesn’t have a VPC and I can’t configure DNS peering.
Interesting to tell that in a vm in apigee project I can resolve this name, but don’t in portal (https://apigee.google.com/).