The `.gz` extention indicates that the file is compressed, so that explains the small size.
I have a hunch (supported by a similar thread I found), that it might be a firmware issue (either missed updates or corrupted files), so you could try to update that as well.
If all else fails, for now, a workaround would be to uncompress the `.gcode.gz` file, and try to print that (or save to `.gcode` file, then print from that file)... though this is hardly ideal of course.