Problem setting up my replication to my remote elasticsearch cluster
Version 3 of the Couchbase Elasticsearch connector requires the target index to already exist. You'll need to create the 'bankable' index in Elasticsearch first.
If that's not the problem, take a look at the Elasticsearch logs; that's where any connector error messages will appear for version 3.
By the way, I strongly encourage upgrading to version 4 of the connector. It uses a more robust replication mechanism and is the focus of future development.
Disclaimer: I work for Couchbase and maintain the Elasticsearch connector.