how can I copy custom exif fields from one image to another with exiftool?

I am trying to copy all metadata from one image to another, including custom exif fields (in this case absolute and relative altitudes present in images from my DJI drone) using the command:

exiftool -tagsfromfile orig.jpg -all:all new.jpg

however only the standard tags are copied:

exiftool -s orig.jpg | grep -i alt

> GPSAltitudeRef                  : Above Sea Level
> AbsoluteAltitude                : -10.68
> RelativeAltitude                : +60.90
> GPSAltitude                     : 60.9 m Above Sea Level


exiftool -s new.jpg | grep -i alt

> GPSAltitudeRef                  : Above Sea Level
> GPSAltitude                     : 60.9 m Above Sea Level

Is there any way to copy all the tags across automatically, or do I have to add them one at a time?

Thanks for your help