Pixhawk 4 and Ublox NEO-M8N GPS

Update: after trying all evening again i’ve finally managed to calibrate the internal mag on QGroundControl by installing an older version of PX4 (1.5). I also managed to see the internal mag and external mag, but could not calibrate the external so have had to unplug it. Ideal scenario would be to run the external mag as primary and internal as backup, on the latest version of Pixhawk, so if anyone has any suggestions that would be amazing. It seems like there is an issue with the mags being correctly identified (hence the no uorb devid mag ID error) but I have no idea how to sort it!