I got some raw files from a friend who uses the same camera model as me (Nikon D750). I notice that whereas I can postprocess my NEF pictures just fine, his pictures look very very weird when I try to open them (the integrated NEF thumbnails look ok, but that's it). He confirmed that he also cannot edit his pictures in anything else but Lightroom.
Can you help me figure out what's going on? I assume there's some setting in the camera that scrambles the channels in some way only Lightroom can make sense of?
And this (warning: 24 MB file) is the NEF file from the screenshot above.