iPad Mini 6 asks for login password when backing up
iPad Mini 6 running iOS 15.7.1 backing up to Mid-2011 iMac running MacOS 10.13.6 via both iTunes 12.8.3 and iMazing 2.16.2
I back up my 3 iDevices weekly using both iTunes & iMazing via USB. The other 2 are an iPad Mini 5 running iOS 14.4.2 and an iPhone 12 running iOS 16.0.3. Today for the first time after I click on "Backup" in either iTunes or iMazing, the Mini 6 asked both times for my log in password but neither the Mini 5 nor the iPhone did. All were unlocked already so this is weird.
Can anyone throw some light as to why all of a sudden the Mini 6 has started doing this? I can't find a setting for backups in the Mini 6 that would cover this.
iPad mini 6 Wi-Fi