Corrupted Contacts after upgrading to iOS16, due to new vCard format?

Posting on here to see how widespread this problem is, and to see what solutions users/Apple have come up with, and for any advice that others can provide.

BACKGROUND

In October, 2022 I upgraded my iPhone and iPad to iOS16 (they are currently running 16.3). At the time my Mac was still on Monterey (it's now running Ventura 13.2). 

Luckily, I took advantage of iCloud Backup which allowed me to delete the contacts from all of my devices, including on iCloud, and then roll-back my contacts to a few days prior to the iOS16 update and quickly export them in .abbu file and individual vCard files. Unfortunately the contacts got re-corrupted but I was able to import the vCard files (Lists, formerly Groups not present though) into another user account which has the 'Contacts' turned off in iCloud settings, so I have been popping into that user account and copying missing information such as lost notes into the Notes App, which then syncs to my main user account, where I can view them. I called Apple Support and alerted them to this issue

I have recently reached out to Apple Support a second time to try and get on top of this. Luckily, I have a fully intact collection of contacts pre iOS16 upgrade, exported both a 165MB Contacts Archive .abbu (address book back up) file, as well exported all 26MB of vCards (by selecting them all and dragging them into a folder). The .abbu file is larger as it contains the List (Group) information. My predicament though, is that I continue to add to and modify my contacts, so if I roll-back to pre iOS16 install, I will loose my recent changes and additions.

To date, my current Apple Support agent :

1.    Checked and confirmed that no other 'Accounts' were accessing/syncing my contacts. For disclosure I do have M365 Business Subscription for work, but I do not use Outlook Contacts at all. It is empty. I have not installed any 3rd party apps or connected my iCloud services to any other vendors such as Microsoft, Yahoo or Google.

2.    Got me to restore from iCloud backup, but Apple only retains about a week of backups, so that was no use. 

3.    Suggested I delete all contacts from iCloud and devices, then import my exported vCards. I rejected that idea on the grounds that the vCards will not be assigned to any Lists, as only .abbu files contain the contacts + associated Lists (Groups).

I then advised the agent that it would be better to import the Contacts Archive .abbu file. We tried this, but it won't import. Contacts App will export a 165MB Contacts Archive .abbu file, but it will not re-import it (perhaps because of a new vCard format that Apple implemented?). We left the Mac (it's a 2022 M1 Pro 14" MacBook Pro) alone for over an hour, but it was doing nothing. The import process just jumps to the finished line and presents an empty list of contacts. Basically it failed due to some unknown issue, which I believe could be a change in vCard implementation.

I'm waiting for my support agent to call back with a solution, but it's all looking pretty dire and getting messier as each week passes with me retrieving notes and moving them out of Contacts App and into the Notes App (separated from the contact that the notes are related to). 

In summary, this problem started the day I updated to iOS16, and I believe it is related to how iCloud syncs vCards between Apple services, and devices running the updated versions of iOS16 and macOS13 Ventura. I am wondering if Apple has implemented a new vCard format but not got the transition for existing pro users like myself to work. I can imagine for 99% of Mac users, they would not run into this issue, but I'm sure some rusted on Apple users may be able to relate to this post.

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CORRUPTION ERROR: X-ABShowAs:COMPANY

Initially I noticed that some of the contacts had had the 'notes' field corrupted, with the end portion of the notes missing, replaced by a string of text: X-ABShowAs:COMPANY 

These seems to be many/most (but not all) contacts where the contact card was created as a 'Company'. 

CORRUPTION ERROR: Item2.X-ABLabel:_$!%3CHomePage%3E!$_X-ABShowAs:COMPANY

Contacts where the field 'homepage' was added are now corrupted to 'correct URL followed by: Item2.X-ABLabel:_$!%3CHomePage%3E!$_X-ABShowAs:COMPANY eg: http:/www.apple.comItem2.X-ABLabel:_$!%3CHomePage%3E!$_X-ABShowAs:COMPANY

CORRUPTION ERROR: item1.X-ABADR

Contacts where the field 'Country' was added are now corrupted to 'Correct Country Name followed by: item1.X-ABADR:gb eg: United Kingdomitem1.X-ABADR:gb

CORRUPTION ERROR: item1.X-ABLabel

Contacts where I created a 'custom field' for phone number such as: 'own', are now corrupted to 'correctmobilenumber followed by: item1.X-ABLabel:own' eg: 123456789item1.X-ABLabel:own

[Personal Information Edited by Moderator]