I have nothing but stellar results with mine, better than any other device I have tried. Was your phone near the shore and switched on? If so it might be skewing the gps. Also, technique can be a factor (not inferring yours is bad of course) but a strong, long pull & longer glide phase means longer recovery and more chance of picking up gps when your wrist is out of the water.
[doublepost=1565619504][/doublepost]Here is my swim from yesterday...