Don't you have to check the box next to a folder name, or the box next to All Folders?
Checking the box next to a folder name, or the box next to All Folders, does not change the problem - import remains greyed out.
Check the box next to "All Folders" and post another screen shot with that box checked.
Look at the next section down, "New Photos", and see what the number is. If it is NONE then whatever catalog you are trying to import from those images already exist in the catalog you have open.
Just Shoot Me (well, I'm not quite that hopeless yet) here is the screen shot with "All Folders" checked - the number of "New Photos" is zero. If the images already exist, where are they? They don't show up on the folders list on the left palette, and they don't show up when I search by text attribute using the name(s) of specific files/photos. When I search by other criteria in the metadata, LR seems to sort of find the photos, but they are just grey squares with exclamations points - see final image below. Perhaps my question now is, how else can I search for the images within LR?
As stated in my original post, when I open the straight IMPORT dialog (as opposed to the one within IMPORT FROM CATALOG,) the images are greyed, so they do seem to be in the LR catalog, but I can't find them. They are in a parent folder that is different than any of the other images in this LR catalog. I've also attached below a grab of the folder hierarchies in both LR and the Finder, to show that the Amalfi & Rome folders are in the same top folder as other images that are in the LR catalog, but nested in a folder that I can't see in LR. I don't understand why in the LR catalog, the "Amalfi & Rome 2016" folder doesn't show up between the "Agrigento.." and "Concha Positano.." folders.
btw, the "Missing Photographs shown under "Catalog" are not from the folders in question, i.e. there are far more photos in the folders I can't locate, and when I look at those "missing photographs," I see they are from other locations.
Again, THANK YOU for taking the time to read through and think about my problem. It's so kind of you.
Missing photographs are ones that ARE IN the LR catalog but LR can't find them. IE, they are no longer in the original location they were in when they were imported.
That also means you can't and definitely should not try to re-Import them.
You would use either Find Missing file or Update folder/file location.
LR is just a database program. No files are ever IN LR. They are only referenced into the LR database file, the Catalog file, from where they are stored on your hard drives.
You somehow moved or deleted the original images and that is why LR can't find them. But they are referenced in the catalog.
You need to search your hard drives for them. Maybe they were on an external drive that is not currently connected?
Thank you, JSM, for helping me figure it out! The images are not on a disconnected HD, but LR thought they were in that previous location. It never occurred to me to drop down the disclosure/expansion/rotating arrows/triangles for all drives on the left Library palette. I kept expecting to find the folders/images where they actually are located. I hope that makes sense to readers. Thanks again!