I'm not sure if my unit is defective or if this is a bug. I clicked the walk activity, walked for about a mile, then paused it and clicked resume later. A short while after, I resumed the activity, and when I got home and looked at Garmin Connect, the latter part of the walk was missing. I tried this again, and this time, the latter part of the walk is there but there's severe errors like the GPS signal is missing in places (a straight line goes from a to b). I checked for the GPS thing to go green before I walked anywhere. I didn't experience these problems with the previous model.
I have my watch set to record every second, with GPS and GLONASS enabled. I'm 99.999999% certain this is not user error.