Did you ever get this one sorted out? Trying to get ngrok working on macOS for our users and hitting a wall at the moment.
They tried setting the root_cas global option to "host" and also to the direct location of the nscacert.pem file but that didn't work:
Session Status reconnecting (failed to send authentication request: session closed).
Thanks aramachandran but I don't know if this will help with SSL decryption - as that is the real cause of the error here?