Unable to use custom plugin in confluent cloud

We have built a custom SMT for postgresql jdbc sink connector. We are trying to use this custom SMT along with JDBC sink connector as a custom plugin in confluent cloud. We have followed all the steps described at Custom Connectors for Confluent Cloud | Confluent Documentation, but once we start the custom plugin we don’t see any error or activity. Is there something we are missing to use custom plugin in confluent cloud?