RAW FILES

This is an old tutorial from Lightroom 5. But the import process is the same, and I like this person's teaching style. Personally, I think she is very thorough and precise. So take a look and see what you think.

https://www.youtube.com/watch?v=867ysQfh4sU&t=236s

I'm not aware of another version of that program. I hadn't looked at the models that it supported. Sorry. I guess your best choice will be to do your raw editing with ViewNX, and then save tiff files that you can then import into Lightroom. Then, from this point forward, just use the import feature in Lightroom to download the images from your camera card. Do you need a reference tutorial to help you understand how to import using Lightroom?

Nikon Transfer has been notorious for doing something to NEF files that make them not readable by Lightroom. There is nothing "magical" about that software that necessitates using it. My suggestion would be for you to simply use the import utility that is part of Lightroom in the future. It works very well for me. However, to solve your problem, there is a utility you can run that will repair your NEF files so that they can be read by Lightroom. Here is the link to where it can be downloaded:

https://exiftool.org/fix_corrupted_nef.html

Is there any chance you used Nikon software to download the images from your camera?

What happens when you try to add the raw files? Are there any error messages? If so, what is the exact error message?

What camera do you have? Is it a new model? See this table:

Cameras supported by Camera Raw