Brightscreen for D800 & D800e

Several split image finder screens - I've had both Nikon and Brightscreens - will go black in the split image area over a certain focal length. Nikon's literature goes through every lens they've ever made and gives you a "works fine, dicey, won't work" but Brightscreen does not. I had a Brightscreen split on my Bronica 6x6 bodies, but when I went to 150mm or longer, had to swap them out.

Maybe they've figured out how to solve it, but I think it's an optics thing.