Not saying that this is definetely the case, but it might be similar to what I experience with failing software updates.In the app (in Garmin Devices) it shows "Sending software update" and a very slowly filling progress bar that will eventually display "failed", and it starts over again. After a few days this will end. It results in rather big chunks of data being downloaded (and rapid phone battery drain). Since I have switched off automatic updating (update the watch via USB) this has stopped.
