I had exactly the same thing happen. I've been using Retro and the Client software for many years and tried everything I know to get the Client to work. Result = nada. Could not get it to work. Retro could see it, but could not find to configure it.
Solution... trash the Client update (v. 6.2.229) and reinstall the previous version (6.1.139). This immediately worked for me.
I don't know what is wrong with the Client software, but it did not work on my MacBook Pro.
Mac