Are you able to see the preview of the Images, what is the error message coming up.
And you can check for the update by clicking on the Help in Lightroom and choosing Updates.
Please make sure your Lightroom is updated as mentioned above.
Also make sure you are not using Nikon transfer as there have been issues reported that nikon transfer corrupts the raw files. Try to copy and paste the files from memory card to local drive and then try to import the files in Lightroom.
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