After Import, the folder shows as empty in Folders panel but Finder shows the images are there.

A couple of points to make, in addition to what @JohanElzenga said:

Lightroom Classic is not a file browser like Mac Finder or Windows Explorer. It does not have to show the same arrangement of photos in folders as Mac Finder or Windows Explorer; and the most likely reason for that is user mistake, where as stated the user has imported via COPY instead of ADD. So LrC knows about the Copy in some folder somewhere, and it doesn't know about the original photo in the folder you are looking at in Mac Finder or Windows Explorer.

You need to find these photos in Lightroom Classic. Please follow all four of these steps in the Lightroom Classic Library Module, in order.

1. Click on All Photographs (its on the left under Catalog)
2. Turn off all filters (Ctrl-L once or twice)
3. Expand All Stacks (Photo->Stacking->Expand All Stacks)
4. In the Filter Bar, search for a photo by File name

Once you find them, we can provide instructions for fixing LrC so that the file now appears in LrC in the folder you want, that matches Mac Finder or Windows Explorer.

Most likely you used 'Copy' at the top center of the import dialog, so Lightroom copied the photos to another folder and only shows those copies, because only those copies are in the catalog. That's a common mistake. If you want to import images and keep them in their current folder, then you must select 'Add'.