From your post, it sounds like you are using CBL 1.3.1.
However, I have already verified connectivity through simple GET requests, by creating a custom SSLSocketFactory / HostnameVerifier (custom SSLFactory is passed to Couchbase Module, custom HostnameVerifier is set as default by HttpsURLConnection.setDefaultHostnameVerifier).
What is the Couchbase Module? Can you provide some code to understand how the self signed certificate is passed to the HTTPClient? And whether you are using the Couchbase Lite replications or sending HTTP requests to the Sync Gateway REST API “directly”?