Photos imported to LrC not showing in Library. However when trying to repeat import image is greyed out as already imported. Show in finder reveals file in appropriate folder. Filters are off and no stacking.

If you can right-click an image and choose ‘Show in Finder’, then that means the image is shown in Lightroom. If not in the Library, then where are you when you right-click the image? And what do you mean with ‘in the Library’ in the first place? The Library is a module. In that module you can select a folder, a custom collection, or one of special collections like ‘All Photographs’ or ‘Previous Import’. So what have you selected when you expect to see the image, but don’t?

Photos are greyed out because they have already been imported. You should not import photos more than once.

The problem is that you probably imported the photos using COPY instead of ADD, and so LrC thinks the photos are in a different folder (where they were copied to) than you think they are in. So you need to find the photos in LrC by following all four of these steps in order.

1. In the LrC Library Module, click on “All Photographs” on the left under Catalog
2. Expand all stacks (Photo->Stacking->Expand all stacks)
3. Turn off all filters (Ctrl-L once or twice)
4. Search for one of these photos in the LrC Library Module Filter Bar, by file name.

You will see the photo that you searched for after step 4. The others are also in the same folder.