I've recently discovered that when I edit the title of an activity in the Garmin Connect Android app, the calories are removed from that activity. Viewing the activity in the app or on the website after that shows 0 calories. If I renamed it via the website, the calorie data is safe
Try the new GCM version. 4.4... It should be fixed now.....hopefully... I haven't tried it, I'm on an old version of GCM that works. let us know how you get on if someone upgrades.. :-)