pt-online-schema-change for RDS instance with Read Replica behind VPC


I require running pt-online-schema-change for a MySQL 5.6 DB instance under AWS RDS.
The same instance is behind a VPC, and it has a Read Replica. AWS manages its VPC read replicas under a different subnet than the original instance.

How would you go about executing this tool in this case?
When I tried doing it using --recursion-method
No slaves found. See --recursion-method if host has slaves.
Not checking slave lag because no slaves were found and --check-slave-lag was not specified.
Can’t use an undefined value as an ARRAY reference at /usr/bin/pt-online-schema-change line 7135, line 1.

Is it possible that the replication under the VPC works with a different IP than the “public IP” of the Replica, and that’s why Percona is unable to discover the replica?

Thanks for your assistance,