Unable to import from SD Card

[seizer1975]

I am familiar with Lightroom and know my way around, but am not a "power user". I have a client who is experiencing an issue with importing from an SD card. The images are marked as "already imported", but they are not.

First the stats:

Late 2015 27" running Catalina 10.15.7 with plenty of storage space running Lightroom Classic 11.2. 

Here's what I have tried:

trying different SD cards

formatting the SD cards, both in-camera and using Disk Utility

checking permissions on the SD card

checking Lightrooms "Files & Folders" access in "Security & Privacy" in System Preferences

import the same images from a folder on the desktop, which worked.

import the images into a new Catalog, which worked.

turning "Don't Import Suspected Duplicates" on and off

I have not tried:

uninstalling Lightroom (previous posts regarding this issue have suggested this does not make a difference)

upgrading macOS (didn't have time to do so on my visit)

Thank you in advance for any suggestions you may have.

[Abambo]

Just for the test. Copy them to a stick or a different external disk. Try to import. Importing from the desktop has different defaults. Pictures won't be copied by default.

import the images into a new Catalog, which worked.

By @seizer1975

And import from that catalogue?

Also: is this specific to these photos, does it not import any pictures? Test to do: some newly shot pictures, try to import.