[Bug]: iOS contacts can't set default *list*

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration/webserver/proxy issue.
• This issue is not already reported on Github OR Nextcloud Community Forum (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

I am using iOS 16.5.1 with CalDAV set up for my NextCloud instance. The NC instance has multiple Contact Groups. On iOS, these Contact Groups translate to lists (iOS lingo). See the following screenshot:

To avoid confusion: It is possible to set the default account in the iOS settings by navigating Settings > Contacts > Default account. However, it is not possible to set the default list / Contacts Group.

New contacts are always being added to one group, but not the main All Contacts group. Now you may ask: why open an issue in nextcloud/server? Well, I don't think iOS will magically and easily change. So I think it makes sense to first understand whether some server settings / code affect the default contact placement.

Steps to reproduce

1. set up CalDAV sync on an iOS device
2. create multiple contact groups in NextCloud
3. sync
4. create a new contact on iOS and observe that it is added in one of the Contact Groups

Expected behavior

it gets added to the All Contacts group.

Installation method

Community Docker image

Nextcloud Server version

27

Operating system

Debian/Ubuntu

PHP engine version

PHP 8.1

Web server

Apache (supported)

Database engine version

MariaDB

Is this bug present after an update or on a fresh install?

None

Are you using the Nextcloud Server Encryption module?

Encryption is Disabled

What user-backends are you using?

• Default user-backend (database)
• LDAP/ Active Directory
• SSO - SAML
• Other

Configuration report

{
    "system": {
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "tempdirectory": "\/data\/tmp",
        "supportedDatabases": [
            "sqlite",
            "mysql",
            "pgsql"
        ],
        "logtimezone": "Europe\/Berlin",
        "logdateformat": "Y-m-d H:i:s",
        "memcache.local": "\\OC\\Memcache\\APCu",
        "apps_paths": [
            {
                "path": "\/var\/www\/apps",
                "url": "\/apps",
                "writable": false
            },
            {
                "path": "\/data\/userapps",
                "url": "\/userapps",
                "writable": true
            }
        ],
        "default_locale": "de",
        "default_phone_region": "DE",
        "mail_smtpmode": "smtp",
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "cloud.patz.app"
        ],
        "trusted_proxies": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "mysql",
        "version": "27.0.0.8",
        "overwriteprotocol": "https",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbport": "",
        "dbtableprefix": "",
        "mysql.utf8mb4": true,
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "installed": true,
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_sendmailmode": "smtp",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpauthtype": "LOGIN",
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpport": "587",
        "debug": false,
        "loglevel": 2,
        "maintenance": false,
        "app_install_overwrite": [
            "occweb",
            "drawio",
            "extract",
            "gpxpod",
            "electronicsignatures",
            "files_markdown",
            "files_mindmap",
            "socialsharing_email",
            "maps"
        ],
        "theme": "",
        "allow_local_remote_servers": true,
        "overwrite.cli.url": "https:\/\/cloud.patz.app",
        "mail_smtpauth": 1,
        "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
        "mail_smtppassword": "***REMOVED SENSITIVE VALUE***"
    }
}

List of activated Apps

Enabled:
  - activity: 2.19.0
  - admin_audit: 1.17.0
  - calendar: 4.4.3
  - circles: 27.0.0
  - cloud_federation_api: 1.10.0
  - comments: 1.17.0
  - contacts: 5.3.2
  - cospend: 1.5.10
  - dav: 1.27.0
  - deck: 1.10.0
  - drawio: 2.1.1
  - electronicsignatures: 2.0.5
  - extract: 1.3.6
  - federatedfilesharing: 1.17.0
  - federation: 1.17.0
  - files: 1.22.0
  - files_accesscontrol: 1.17.0
  - files_automatedtagging: 1.17.0
  - files_markdown: 2.4.1
  - files_mindmap: 0.0.28
  - files_pdfviewer: 2.8.0
  - files_rightclick: 1.6.0
  - files_sharing: 1.19.0
  - files_trashbin: 1.17.0
  - files_versions: 1.20.0
  - files_zip: 1.4.0
  - firstrunwizard: 2.16.0
  - forms: 3.3.1
  - gpxpod: 5.0.12
  - groupfolders: 15.0.0
  - integration_google: 2.0.2
  - integration_openproject: 2.3.7
  - logreader: 2.12.0
  - lookup_server_connector: 1.15.0
  - mail: 3.2.3
  - maps: 1.1.0
  - nextcloud_announcements: 1.16.0
  - notifications: 2.15.0
  - oauth2: 1.15.0
  - onlyoffice: 8.1.0
  - password_policy: 1.17.0
  - photos: 2.3.0
  - previewgenerator: 5.3.0
  - privacy: 1.11.0
  - provisioning_api: 1.17.0
  - recommendations: 1.6.0
  - related_resources: 1.2.0
  - serverinfo: 1.17.0
  - settings: 1.9.0
  - sharebymail: 1.17.0
  - socialsharing_email: 2.6.0
  - spreed: 17.0.1
  - support: 1.10.0
  - survey_client: 1.15.0
  - suspicious_login: 5.0.0
  - systemtags: 1.17.0
  - tasks: 0.15.0
  - text: 3.8.0
  - theming: 2.2.0
  - twofactor_backupcodes: 1.16.0
  - twofactor_totp: 9.0.0
  - updatenotification: 1.17.0
  - user_oidc: 1.3.3
  - user_status: 1.7.0
  - viewer: 2.1.0
  - weather_status: 1.7.0
  - workflowengine: 2.9.0
Disabled:
  - bruteforcesettings: 2.7.0 (installed 2.4.0)
  - contactsinteraction: 1.8.0 (installed 1.7.0)
  - dashboard: 7.7.0 (installed 7.0.0)
  - encryption: 2.15.0
  - files_external: 1.19.0 (installed 1.16.1)
  - user_ldap: 1.17.0

Nextcloud Signing status

no errors have been found

Nextcloud Logs

-

Additional info

Start by tracing the server-side CalDAV contacts handling for iOS contact groups and the default placement of newly created contacts. Compare the reported behavior with the expected All Contacts group, then identify the relevant server setting or code path and reproduce the case with multiple contact groups; done means new iOS contacts are placed in All Contacts as expected.