LrC Import - Major Malfunction

Major malfunction with Lightroom Classic:
I tried to Import (Copy) about 20 images from my CF Express card to my local SSD - exactly as I always do.
The Import dialog window gets stuck with no progress and never ends, for a task that should take a few seconds. In the Import dialog window, the image thumbnails don't render any images and display only as grey boxes. I Forced Quit, ejected the card, restarted my Mac, reinserted the card and from Finder I dragged (copied) the images into my Users > Pictures folder on my local SSD. No problem. Relaunched LrC and ran the Import process again, and again the same issue. Forced Quit again and restarted my Mac. Again, I tried to Import (Add) but again had to Force Quit when the Import dialog window got stuck. 
I restarted my Mac again. Tried Library > Synchronise Folder but it just froze and I had to Force Quit.
When I cancel the Import process, I get a dialog box saying "no photos or videos were found to import" even though they’re on my local drive. I tried deleting the LrC Preferences file which also has not resolved the issue.
I’m able to view the same images in Bridge, open and edit them in Photoshop so the issue most certainly is the Import process. In the Import window I cannot see any image thumbnails in any folders on my computer. In the screenshot of the Import window I have selected my entire Pictures folder which shows no rendering of any image thumbnails.

As a final test, I was able to Import the same images into LrC from the CFX card onto my other Mac with no issues, so the issue definitely cannot be the CF Express card, nor the card reader, nor my images.