This weekend I was navigating a course, which I shared with my wife. She loaded the gpx on her Wahoo, I had it loaded on my 530. We took a shortcut and after 500 m we were back on track. After this, my wifes Wahoo was fine, but my 530 kept indicating a U-turn for more than 5 km. Every 500 m the track was found again, and after recalculating a U-turn was indicating while the map was clearly indicating to go straigth on.