Syncing iPhone 17 Pro Max to MacBook Air fails

iPhone 17 Pro Max

MacBook Air M3 2024

MacOS Sequoia 15.7.3

Sync fails with iPhone 17 Pro Max to Macbook Air, connected via usb C (original iPhone cable) and using Finder interface. First the process got stuck at step 2, calculating -- waited several hours with no progress. The latest error reports: 'Waiting for changes to be applied'.

What I've done so far:

• Checked cable connection (cable is original USB C cable that came with the iPhone)

• Performed software updates on both iPhone and MacBook Air

• Force-restarted iPhone and restarted MacBook Air, plugged the iPhone in again (lost count of how many times)

• Put iPhone into airplane mode

• Searched for and didn't find MDCrashReportTool in Activity Monitor (presumably this bug has been fixed)

• Turned off Lock Screen on iPhone and set MacBook Air to never sleep

My intention is to back up the iPhone to the MacBook Air and subsequently move it to an external hard drive. Directly backing up to the hard drive is not possible (uses USB A).

The iPhone has successfully synced to iCloud, so why is it unable to sync to the MacBook Air?

Could it be a conflict with ownership? The MacBook Air is using my Apple account whereas the iPhone uses my husband's Apple account.