Having issue while transferring photos from iPhone to Mac Pro

I've already asked a few times, but I'm no closer to having a reason why sometimes things work and sometimes they don't: I have an iPhone 15 Pro Max with IOS 18.0.1 I have a Desktop MacPro with MacOS 15.0.1. Everything is up to date. I have plenty of disk space on both my iPhone and on my Mac Pro.

I --- used --- to be able to move photos easily from my iPhone to my Mac Pro, in the standard way by connecting the iPhone to the Mac Pro via a cable. Now sometimes this works and SOMETIMES (too often) IT DOESN'T. I've been doing this for years, and I'm using EXACTLY the steps I've always used. Open photos on the Mac Pro, open the iPhone and plug it into the Mac. SOMETIMES the photos from my iPhone populate the Mac Pro photos app. And sometimes THEY DON'T. Instead I see a bunch of empty squares and nothing happens.

Why it works or doesn't work seems random, like maybe the time or day or whether the astrological stars are aligned. BTW, my iCloud account is full, but I don't care. I have ROOM ON BOTH DEVICES and that is where I want to keep my photos. Is Apple now unhappy with this idea? Is Apple trying to make me pay for iCloud upgrade? If so, making features not work is not a good way to accomplish this - it's the kind of trick that makes customers not trust a company.

[Re-Titled by Moderator]