I have a starling 2 with the default GPS. When I write "px4-listener sensor_gps" I receive: "never published". When I looked at the startup log I see that it is searching and not connecting to any gps, constantly printing the following lines:
GPS UART baudrate set to 115200
Dec 12 10:19:56 m0054 voxl-px4[22983]: INFO [muorb] SLPI: GPS UART baudrate set to 9600
Dec 12 10:19:56 m0054 voxl-px4[22983]: INFO [muorb] SLPI: GPS UART baudrate set to 38400
Dec 12 10:19:56 m0054 voxl-px4[22983]: INFO [muorb] SLPI: GPS UART baudrate set to 57600

when I run the gps status command I see in the log:

Dec 12 10:36:46 m0054 voxl-px4[1942]: INFO [muorb] SLPI: Main GPS
Dec 12 10:36:46 m0054 voxl-px4[1942]: INFO [muorb] SLPI: protocol: UBX
Dec 12 10:36:46 m0054 voxl-px4[1942]: INFO [muorb] SLPI: status: NOT OK, port: 6, baudrate: 0
Dec 12 10:36:46 m0054 voxl-px4[1942]: INFO [muorb] SLPI: sat info: disabled
Dec 12 10:36:46 m0054 voxl-px4[1942]: INFO [muorb] SLPI: rate reading: 0 B/s
Dec 12 10:36:46 m0054 voxl-px4[1942]: INFO [muorb] SLPI: Ok executing command: gps status
Thanks!