Problem with Federated Query to RDS Assert code: 1000

We are connecting Redshift with RDS using Federated Queries. When we try to query very simple tables like Month (id (int4) / name (text)) or Practices (text,text,text) from Postgres, we have errors like:

ERROR: ----------------------------------------------- error: Assert code: 1000 context: reltuples >= 0.0 - Number of rows cannot be negative query: 0 location: pgclient.cpp:288 process: padbmaster [pid=14019] ----------------------------------------------- [ErrorId: 1-630676b5-594e911339e1d0341291f074]

One useful information: we enabled enable_case_sensitive_identifier = True because the names of the tables on RDS were PascalCase.

The tables are small, so I don't know if a query optimization engine is causing such errors.

Any information would help us. Thanks in advance.