I'm having a similar problem. On my connect screen, however, it shows that I must have switched timezones. I have not. I've posted this in the Android - Connect forum since the device seems to count correctly. Maybe I should have posted here instead.
Is there a chance you are seeing the timezone warning too?
Thanks.
Mine was working close enough until today as well. I called Garmin on Wednesday after my watch froze to figure out how to get the steps back on it. They told me I wouldn't get credit for more steps until I went over 7,200 again. I told them about the calorie issue too. They said it may be a defective unit and would help me delete files that may be corrupted. I followed the steps and then reset the watch as a new unit. It was closer on Thursday, Friday, and Saturday so I thought it was good enough. I'll be calling again tomorrow since it is way off today after running 10 miles after church.
10 mile run - 18,000+ steps - 879 calories (normal)
All day activity - 5,000+ steps - 994 calories (what???)
I'm not sure how I got so many calories for 5,000 steps (see attached). GC says I've burned 3378 calories total today. My watch says I've burned 2525 (see attached for data right after my run). That means my calories from my run got almost doubled. MyFitnessPal uses the GC number, so it's hard to track my calories throughout the day when I have no idea what my actual projection is (see attached).
I am still awaiting feedback from Garmin support (both local and international support). I had created several tickets some 2-3 weeks ago. I'm starting to think they will not get back to me at all - Very dissapointing. I'd be fine with them not getting back to me if the issue(s) got fixed but not getting back to me and still not fixing the issues is unacceptable.
However, just because there is a double counting issue, doesn't mean there isn't also some heart rate sampling/calories quoted issue too, it's just a seperate one.