Mit deinem Input bekomme ich auch nur eine leere gpx, aber mit dem Beispiel von oben funktionierts. Sind in dem Beispiel überhaupt valide Koordinaten?
Edit: der Input für das erste Beispiel:
$GPRMC,100438.00,A,5338.17418,N,00955.26888,E,25.789,144.15,110317,,,A*52
$GPVTG,144.15,T,,M,25.789,N,47.761,K,A*3A
$GPGGA,100438.00,5338.17418,N,00955.26888,E,1,07,1.28,10.2,M,45.1,M,,*6E
$GPGSA,A,3,30,20,05,28,13,09,07,,,,,,2.15,1.28,1.73*08
$GPGSV,3,1,12,02,05,226,,05,62,247,30,07,46,064,38,08,06,067,*79
$GPGSV,3,2,12,09,19,103,25,13,37,279,26,15,05,285,15,20,27,308,20*75
$GPGSV,3,3,12,21,07,339,16,27,09,033,16,28,27,150,23,30,79,137,39*73
$GPGLL,5338.17418,N,00955.26888,E,100438.00,A,A*64
$GPRMC,100439.00,A,5338.16859,N,00955.27594,E,25.134,144.36,110317,,,A*5B
$GPVTG,144.36,T,,M,25.134,N,46.548,K,A*33
$GPGGA,100439.00,5338.16859,N,00955.27594,E,1,07,1.28,11.3,M,45.1,M,,*66
$GPGSA,A,3,30,20,05,28,13,09,07,,,,,,2.15,1.28,1.73*08
$GPGSV,3,1,12,02,05,226,,05,62,247,35,07,46,064,27,08,06,067,*72
$GPGSV,3,2,12,09,19,103,24,13,37,279,26,15,05,285,17,20,27,308,19*7C
$GPGSV,3,3,12,21,07,339,16,27,09,033,15,28,27,150,30,30,79,137,34*7F
$GPGLL,5338.16859,N,00955.27594,E,100439.00,A,A*6C