iPhone 13 dng files not appearing when copying to Lightroom

I routinely copy photos from my iPhone 13 to Lightroom on my MacBook Pro through the regular Lightroom import process.   I don't have the "upload photos to iCloud" turned on because it complicates the process of copying files to my computer via Lightroom.  

Lately I've found that many of the photos (seemingly random) don't appear in the Lightroom import screen.   I'm sure it has nothing to do with "Ignore suspected duplicates" because I understand how that function works.   I have the same problem on both computers which are:

MacBook Pro 2020 with Sonoma 14.0 and LR Classic 13.0.   After discovering the problem I updated both the operating system and LR Classic, but the updates didn't fix it.

Mac Pro 2019 (my desktop).  Ventura 13.3   LR Classic 12.4   

Any ideas?