The Camera Raw result depends on the Camera profile being used. Camera Raw uses the profile to decode the raw file.Sorry to revive an old thread, but does in camera custom white balance ever work to begin with???? Or is that just to get you close enough to the ballpark and then you tweak in post?
I bought an x-rite colorchecker passport just for that (coz I felt cheaper chinese knock offs were inacurate) and even when I set a custom white balance in camera using the WB target, whenever I go into Camera Raw there still is a shift when I click on WB over the grey area, it's very confusing and frustrating not knowing which is the correct one. I am lately using the panasonic LX100, but I think I had the same issue with the OMD EM5 as well. Any ideas ????
If you want perfection you need to use the X-Rite Colorchecker and create a camera profile. But that is more work for a small gain. This is what a pro would do when doing an outdoor shoot, and might make several profiles as the light changes.