ADDENDUM: So now I'm in contact with a senior tech type at Apple. Basically had me try everything I have already done, and problem persists. He says he's escalated issue further up the food chain to Engineering.
So here's where we are at:
I have a Mini M2 - it's Contacts' Lists are all intact and no duplication is happening.
iCloud (online) Contacts: Multiple duplicates. Some have two, some have many more. I can delete duplicates. Doing so immediately shows up on a -
MacBook Air (Monterey) Contacts.
iPhone Mini 12 Contacts - deletions in iCloud will eventually show the corrected Lists (if I don't manually delete them from iPhone), but then starts to repopulate with duplicates sometime later. These later then show up back on iCloud.
Purged all the Lists of duplicates with Apple Tech watching yesterday. Then walked away from all devices overnight. This morning - duplicates showing up on iPhone. Opened iCloud (online) - it briefly showed still no duplicates, but then refreshed itself and showed duplicates as on iPhone. MacBook Air reflecting what happened on iCloud.
This is telling me something significantly squiffy with iOS 17.x.x sync to iCloud, and as an experiment I have turned off Contacts sync within my iCloud account on the iPhone (keeping the contacts on the device) and on MacBook. Waiting to see if Duplicates repopulate on any devices. I have emailed Apple tech guy to let him know what I'm trying.
Meanwhile, absolutely no issues with Contacts on my Mac Mini M2 - my primary computer. And all Lists exist on it - while not all Lists are showing up on iCloud / other devices.
Completely, completely random.
