Event data is permanently hidden for everyone, when toggling "Visibility: When shared show only busy"

Steps to reproduce

1. User1: Make a new calendar (user1 is now the owner of this calendar)
2. User1: Share calendar with user2 with edit permissions
3. User1: Make a new event
4. User2: Set event visibility to "When shared show only busy"
   1. User1: Event data is visible
   2. User2: Event data is hidden (title, location, description)
5. User2: Set event visibility to "When shared show only busy"
   1. User1: Event data is hidden (title, location, description)
   2. User2: Event data is hidden Event data is hidden (title, location, description)

And there is no way to get the data back for any users!

Expected behavior

• The event data (title, location, description) should not be hidden for the calendar owner (after step 5)
• The event data should become visible again for all users when visibility is set to "When shared show only busy" (after step 5)
• The event data should still be visible for users with edit permissions (after step 4)

As to the last point, if a shared-with user has edit capabilities, and can change the visibility - it does not really makes sense to hide the data from them.

I think there is a complexity in that "shared" here means all kinds of shared, public and internal both - which should probably be adressed to fix the last expected behaviour

Actual behavior

• After step 5 the event data (title, location, description) is hidden for all users, and it is not possible to get it back.
• After step 4 the event data is hidden for shared-with users.

Calendar app version

5.2.2

CalDAV-clients used

No response

Browser

Firefox 138

Client operating system

MacOS 14.1.1 (23B81)

Server operating system

debian

Web server

Nginx

Database engine version

None

PHP engine version

None

Nextcloud version

Nextcloud Hub 10 (31.0.4)

Updated from an older installed version or fresh install

Fresh install

List of activated apps

Enabled:
  - activity: 4.0.0
  - admin_audit: 1.21.0
  - bruteforcesettings: 4.0.0
  - calendar: 5.2.2
  - circles: 31.0.0
  - cloud_federation_api: 1.14.0
  - comments: 1.21.0
  - contactsinteraction: 1.12.0
  - dashboard: 7.11.0
  - dav: 1.33.0
  - federatedfilesharing: 1.21.0
  - federation: 1.21.0
  - files: 2.3.1
  - files_downloadlimit: 4.0.0
  - files_pdfviewer: 4.0.0
  - files_reminders: 1.4.0
  - files_sharing: 1.23.1
  - files_trashbin: 1.21.0
  - files_versions: 1.24.0
  - firstrunwizard: 4.0.0
  - group_default_quota: 0.1.11
  - groupquota: 0.2.2
  - logreader: 4.0.0
  - lookup_server_connector: 1.19.0
  - nextcloud-aio: 0.7.0
  - nextcloud_announcements: 3.0.0
  - notifications: 4.0.0
  - notify_push: 1.0.0
  - oauth2: 1.19.1
  - password_policy: 3.0.0
  - photos: 4.0.0-dev.1
  - privacy: 3.0.0
  - profile: 1.0.0
  - provisioning_api: 1.21.0
  - recommendations: 4.0.0
  - registration: 2.7.0
  - related_resources: 2.0.0
  - richdocuments: 8.6.4
  - serverinfo: 3.0.0
  - settings: 1.14.0
  - sharebymail: 1.21.0
  - support: 3.0.0
  - survey_client: 3.0.0
  - systemtags: 1.21.1
  - text: 5.0.0
  - theming: 2.6.1
  - twofactor_backupcodes: 1.20.0
  - updatenotification: 1.21.0
  - user_status: 1.11.0
  - viewer: 4.0.0
  - weather_status: 1.11.0
  - webhook_listeners: 1.2.0
  - whiteboard: 1.0.5
  - workflowengine: 2.13.0
Disabled:
  - app_api: 5.0.2 (installed 4.0.6)
  - encryption: 2.19.0
  - files_external: 1.23.0
  - suspicious_login: 9.0.1
  - twofactor_nextcloud_notification: 5.0.0
  - twofactor_totp: 13.0.0-dev.0
  - user_ldap: 1.22.0

Nextcloud configuration

{
    "system": {
        "one-click-instance": true,
        "one-click-instance.user-limit": 100,
        "memcache.local": "\\OC\\Memcache\\APCu",
        "apps_paths": [
            {
                "path": "\/var\/www\/html\/apps",
                "url": "\/apps",
                "writable": false
            },
            {
                "path": "\/var\/www\/html\/custom_apps",
                "url": "\/custom_apps",
                "writable": true
            }
        ],
        "check_data_directory_permissions": false,
        "memcache.distributed": "\\OC\\Memcache\\Redis",
        "memcache.locking": "\\OC\\Memcache\\Redis",
        "redis": {
            "host": "***REMOVED SENSITIVE VALUE***",
            "password": "***REMOVED SENSITIVE VALUE***",
            "port": 6379
        },
        "overwritehost": "sky.ukrudt.net",
        "overwriteprotocol": "https",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "localhost",
            "sky.ukrudt.net"
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "pgsql",
        "version": "31.0.4.1",
        "overwrite.cli.url": "https:\/\/sky.ukrudt.net\/",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbport": "",
        "dbtableprefix": "oc_",
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "installed": true,
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "maintenance": false,
        "loglevel": 2,
        "log_type": "file",
        "logfile": "\/var\/www\/html\/data\/nextcloud.log",
        "log_rotate_size": 10485760,
        "log.condition": {
            "apps": [
                "admin_audit"
            ]
        },
        "preview_max_x": 2048,
        "preview_max_y": 2048,
        "jpeg_quality": 60,
        "enabledPreviewProviders": {
            "1": "OC\\Preview\\Image",
            "2": "OC\\Preview\\MarkDown",
            "3": "OC\\Preview\\MP3",
            "4": "OC\\Preview\\TXT",
            "5": "OC\\Preview\\OpenDocument",
            "6": "OC\\Preview\\Movie",
            "7": "OC\\Preview\\Krita",
            "0": "OC\\Preview\\Imaginary",
            "23": "OC\\Preview\\ImaginaryPDF"
        },
        "enable_previews": true,
        "upgrade.disable-web": true,
        "mail_smtpmode": "smtp",
        "trashbin_retention_obligation": "auto, 30",
        "versions_retention_obligation": "auto, 30",
        "activity_expire_days": 30,
        "simpleSignUpLink.shown": false,
        "share_folder": "\/Shared",
        "one-click-instance.link": "https:\/\/nextcloud.com\/all-in-one\/",
        "upgrade.cli-upgrade-link": "https:\/\/github.com\/nextcloud\/all-in-one\/discussions\/2726",
        "updatedirectory": "\/nc-updater",
        "maintenance_window_start": 100,
        "allow_local_remote_servers": true,
        "davstorage.request_timeout": 3600,
        "documentation_url.server_logs": "https:\/\/github.com\/nextcloud\/all-in-one\/discussions\/5425",
        "htaccess.RewriteBase": "\/",
        "dbpersistent": false,
        "auth.bruteforce.protection.enabled": true,
        "ratelimit.protection.enabled": true,
        "files_external_allow_create_new_local": false,
        "trusted_proxies": "***REMOVED SENSITIVE VALUE***",
        "preview_imaginary_url": "***REMOVED SENSITIVE VALUE***",
        "preview_imaginary_key": "***REMOVED SENSITIVE VALUE***",
        "updater.release.channel": "stable",
        "app_install_overwrite": [
            "nextcloud-aio"
        ],
        "skeletondirectory": "\/mnt\/ncdata\/skeleton",
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_sendmailmode": "smtp",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpauth": true,
        "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
        "mail_smtppassword": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpport": "587",
        "DOMAIN": "sky.ukrudt.net"
    }
}

Web server error log

Log file

Browser log

Additional info

No response

Start by reproducing the visibility changes in the Calendar app using the listed two-user sharing steps on Nextcloud Hub 10. Trace how event title, location, and description visibility is handled for owners and users with edit permissions; done means the owner and editors retain the expected data and visibility can be restored for all users.