I've identified the components of the problem precisely. Nik admit to the distorted image when using the splt view. The thumbnails are in a string at the bottom with the image, in question, in the center. And, as noted, it certainly will export properly. However, there's no reason, other than Nik's fault finding with Aperature, that the preview should not work properly.
We're told that it's a GPU issue and have used the option to shut it off, but to no avail. We were told to make some minor changes in the config file and that also was a failure.
I know I've restarted a couple of time, but will look at it again. Again, I am thoroughly distressed with Nik because of it's knowledge of how Aperture functions. So, if you know how Aperture preview functions, then why are you writing software that is inconsistent? Does that mean that Nik is expecting Apple to fix Aperture to its liking?
I have repeatedly touted Nik plugins to be the best on the market today. However, I take expection with this iteration and the way Nik has handled it.