It happened to me too. Try closing the app (some times restarting the pone keeps some apps "open). Try also re-connecting it to the bike.
Also, get in your WiFi.
MC seems to need an overly robust internet connection, especially when you stop recording and it tries connecting to the Specialized mothership. I’ve found closing the app and restarting it after going online via WiFi does the trick. And closing while hung at processing doesn’t seem to harm anything.