Problem may be solved:
With Windows Camera Codec pack installed and the later version of Nikon's NEF codec(v1.27) both installed, there seems to be a problem.
I could tag images in ViewNX2 and Windows Explorer and both would respect each others tagging, and interopability was perfect, but not Windows Photo Gallery.
I reverted back to an earlier version of Nikon's NEF codec(v1.24) and uninstalled Windows Codec Pack, and now can both see the other program's tagged info and write tags via Gallery and both other programs now read those tags too.
problems in codec pack land!
ps. this issue may just be isolated to this PC tho too.
I also have another PC with Win 10 preview installed, and Nikon's v1.27 codec pack(but not Windows codec pack installed) and all is fine on that machine.
either way my issue is about some bug in the codec packs installed.
thanks.