when I import files that are supposedly already imported (but I cannot see them) it doesn't let me. The media remain like with a gray overlay and I cannot import them anymore.
You should not import photos more than once. This is not a good thing to do, it causes confusion and frustration.
You need to find the photos in the Lightroom Classic Library Module. To do this, please perform all four of these steps, in order, in the Lightroom Classic Library Module:
Click on "All Photographs"
Turn off all filters
Expand all stacks (Photos->Stacking->Expand all Stacks)
Search for one of these photos using the Lightroom Classic Filter Bar, search by file name or by capture date
Thanks for your reply. I tried trust me. I found the folder to import to lightroom and it said the folder was empty which was not true. I checked on finder and the images were there. but lightroom classic didn't see them. so odd