Alexander, thanks for the reply. The HTTPS root certificate is trusted. All other HTTPS traffic is working perfectly with Chrome, IE, Visual Studio, etc. The only problem seems to be the join.me Desktop Application.
Maybe it is a problem with Certificate Pinning or something. I'm not sure how to troubleshoot. It seems like you would be able to reproduce it by simply installing the Join.Me Desktop Application and see if it works for you with Fiddler running.