I am connected via a usb-c cable, can see the content of the iPhone photos, it displays even file names, but everything is gray or only a few images show... even if all images are shown, and one or a few selected for import.. it doesn't import, but stalls the process.
1/ ok, but can you see the iphone in the left hand bar on the macos Finder, not just on Lr ?
2/ Is Lr sync turned off (shot in the dark, but could possibly interfere)
3/ Have you tried changing the usb-c cable ?
4/ Can you download images using the built-in Image Downloader in MacOS ?
I can’t compare directly because I'm still using previous generation macos, but did have issues until I paused all cloud syncing.
Trouble shooting is a PITA, If none of the above solve the issue AND you can download images to another similar computer with current MacOS, it may need a clean Lr re-install.
As the French are wont to say …
“Merde” *
Edit:
* French alternative to ‘good luck’.