My FR255s sometimes doesn't pick-up a GPS signal (or very late, like 8 minutes+). Sometimes this also happens during a run which I start with proper GPS signal, after I pause the work-out and resume, the GPS signal is lost. Usually, when I reset the watch (holding the light-button for 15 seconds), the watch works properly for a couple of days.
I have updated to the latest software (does that automatically) and wear the watch 24/7.
Any clues to how to overcome this?