The following article explains what to do if your device loses GPS signal during a round.
If the watch loses GPS signal during the round you will be notified on the screen.
The watch will automatically start to search for GPS in this scenario and, if this happens, you can simply wait for it to do so and the screen will return to yardages.
If you want to end the round at this point press the bottom right button. This will return the watch to the home screen.