also on the import screen the previews for all the .nef raw files dont display at all each one says preview unavailable.
how do i go about importing them viewing them in some way? windows photos wont open them either.
i have the following nikon programs on my computer as well: ViewNX-i, capture NX-D, Nikon transfer 2, picture control utility 2.
the photos behind the pop up in my screenshot are all jpegs but its only the .nef files that wont import. camera body is nikon d3400.
A D3400 NEF file requires at least Lightroom 6.7. So you cannot directly import these into Lightroom 5.7.
You could use the FREE Adobe DNG Converter, convert the NEF to DNG, and then import the photos into LR 5.7.