Running 3.10 on my 235 and using the latest version of Garmin Connect on iOS 9.1 / iPhone 6S / Plantronics BackBeat Fit Bluetooth headphones I've discovered a reproducible bug with volume.
When GC is set have automatic audio prompts of lap times / paces when synced with the 235 it automatically lowers the volume on the music or whatever you are listening to and have a female voice announce the times. Works great. Problem is after the voice is done the volume does not go back up all the way to the previous levels, it seems to have been cut by 25-50%. The bigger issue is that iOS seems to think the volume level is the same as before so trying to increase the volume with controls on the phone, headphones etc. only work to the extent there was room to increase the volume before, it never really lets you return to the previous levels if you were loud to start with. Basically you have a permeant loss of 25-50% volume UNTIL the end of your entire workout when you stop the run on the watch, then the volume suddenly returns to the normal higher levels. I bet the issue in the Garmin Connect iOS software but it is 100% reproducible.
