I'm not sure if this was asked recently, but I have another import problem.I'm using the latest version of LR and Win 10:Lightroom version: CC 2015.2.1
Nikon NEF files turn black after import is complete but visible in Bridge, PS
This is a known issue and Our Engineering team is working on it.
Please follow this link https://helpx.adobe.com/lightroom/kb/thumbnails-display-black-in-lightroom-6-2.html
Here is a Duplicate thread:-Lightroom images turning black
Let us know if that helps