update iphone 16pro from finder via usb does not find iOS 18.7.2

The iPhone itself reports the new Update (18.7.2), and it also offers the option to upgrade to iOS-26 (over the air).

In the iTunes-like Finder window (with the iPhone 16pro connected via USB-C), the Update is not offered.

Clicking the Check for Update button results in the message that 18.7.1 is the current iOS version. Which is not true.

(=> neither iOS 18.7.2 nor iOS 26.1 are recognised)

I am using an iMac24 with Apple Silicon M1 running macOS 15.7.2 to manage my iPhone.

In another thread, I found the hint that the Apple Configurator.app (for Mac) could help. But this App quits after an Internal Error when I ask it to update the connected iPhone.