This is a topic of hot debate at the moment internally, but for right now you cannot enable more verbose logging without making a debug build of the library (I think this will be changing soon but the ultimate direction has not been decided yet).
Couchbase will reject a certificate whose name doesn’t match the host, but you can override it by setting a callback on ServicePointManager.ServerCertificateValidationCallback. For testing purposes you can just have a callback that returns true and it will accept anything regardless of error. If the connection were rejected though you should see a log with an exception. Do you see any logs at all?