If Meshtastic disables NMEA then you will get nothing out of the serial port. UBX requires polling for information.
The link in my first reply contains an Arduino sketch that allows serial pass through to the GPS. You can then factory reset with U Center. This would test the theory that there is a GPS config issue and you could then implement a factory reset or re configuration within your software so it is not an issue in the future.
I’ve changed the sketch for the v07 version. I think this should work.
void setup() {
Serial.begin(9600);
Serial1.begin(9600, SERIAL_8N1, 12, 15, false, 1000); //TBeam v07 GPS defaults
}
void loop() {
if (Serial.available()) { // If anything comes in from the PC,
Serial1.write(Serial.read()); // read it and send it out to the GPS.
}
if (Serial1.available()) { // If anything comes in from the GPS,
Serial.write(Serial1.read()); // read it and send it out to the PC.
}
}