I just did some shooting outside to try the fine-tune-on vs. fine-tune-off settings using the +20 I dialed into the 24-70.
Night and day difference. No ambiguity.
I will be uploading some small images so anybody who wants to see the effect of autofocus fine tune can see it. I had zero interst in autofocus fine tune until now. In my case it is a very big differnce.
The system is misnamed. It should be called the "focus accuracy verification" setting. Or, "self-service quality control and tech support" setting.
Your note to "have it fixed" is my hope too. Whether Nikon can accomplish that is in doubt.