Cosmos database issue - troubleshooting.

We have migrated a Node.js solution from Mongo to Cosmos (or we're trying to). The "cosmos connector" seems to work fine, but the database results we get are not what we are expecting. So the connection works, but something 'inside' cosmos is not working like we expect. We need help troubleshooting this issue. We don't expect it would take long, but we don't know what's broken.