AppDynamics not working on EKS after migrating from Rancher

Question

I'm using a Python application that had AppDynamics working correctly on Rancher, but it stopped working when migrated to EKS. This application is able to connect to AppDynamics and creates the agent, but then its proxy enters in a loop like this:

INFO [AD Thread Pool-Global1] ConfigurationChannel - Sending Registration request with: Application Name MYAPPLICATION, Tier Name [tier-MYTIER], Node Name [node-MYNODE], Host Name [MYHOST] Node Unique Local ID [node-MYNODE], Version [Tags]
Registered app server agent with Node ID[<ID NODE>] Component ID[<COMPONENT ID>] Application ID [<APPICATION ID>]
INFO [AD Thread Pool-Global1] ConfigurationChannel - Auto agent registration attempted: <my application name> Component Name [tier-MYTIER] Node Name [node-MYNODE]
INFO [AD Thread Pool-Global1] ConfigurationChannel - Auto agent registration SUCCEEDED!
INFO [AD Thread Pool-Global1] ConfigurationChannel - Registration information received Node ID[123455] Component ID[<COMPONENT_ID>] Application ID [<APPLICATION ID>]
INFO [AD Thread Pool-Global1] ConfigurationChannel - controllerGUID[null] accountGUID[null]
WARN [AD Thread-Metric Reporter1] MetricHandler - Metric Reporter Queue full. Dropping metrics.

What's happening? I suppose the problem is with the controllerGUID[null] accountGUID[null] but I don't know what is causing that, specially considering that this worked correctly just before the migration