When did the the retroactive breaking change to the create_timeline_item mutation happen?

OK, at some time there has been an undocumented change to the create_timeline_item mutation. You used to be able to send a timestamp in and it would respect that timestamp as the created_at  time.

Example:

mutation createTimelineEntry($customActivityId: String!, $itemId: ID!, $title: String!, $summary: String!, $content: String!, $timestamp: ISO8601DateTime!) {
  create_timeline_item(
    item_id: $itemId
    custom_activity_id: $customActivityId
    title: $title
    summary: $summary
    content: $content
    timestamp: $timestamp
  ) {
    id
  }
}

GraphQL Variables:

{
  "timestamp": "2024-05-08T11:34:39.000Z",
  "customActivityId": "e589f9c3-b4a7-4a7f-bcc1-d6164f4460b7",
  "itemId": 2957556816,
  "title": "🕰️ Historic walk around Sheffield",
  "summary": "Dear John\n\nThank you for signing up to the historic walk around Sheffield, starting at the Peace Gardens. \n\nThe walk will take in some of the city's most fascinating landmarks and stories, from its medieval origins through to its industrial heritage and b",
  "content": "\n                <div><b>From:</b> David Simpson <xxxx@xxxx.onmicrosoft.com&gt;</div>\n\t\t\t\t<div><b>Sent:</b> 2026-05-08T11:34:39Z</div>\n                <div><b>To:</b> xxxxx@outlook.com &lt;xxxx@outlook.com&gt;</div>\n                <div><b>Subject:</b> 🕰️ Historic walk around Sheffield</div>\n                \n                <hr style=\"margin:1em 0\"/>\n                Dear John<br><br>Thank you for signing up to the historic walk around Sheffield, starting at the Peace Gardens. <br><br>The walk will take in some of the city's most fascinating landmarks and stories, from its medieval origins through to its industrial heritage and beyond.<br><br>📍 Meeting point: Sheffield Peace Gardens, Pinstone Street, S1 2HH<br><br>Please see the attached calendar invite for the full itinerary. The walk is expected to last approximately 2–3 hours and is suitable for all abilities.<br><br>It promises to be a wonderful afternoon!<br><br>– David<br>\n            "
}

At some point, this has changed. Now the timestamp entry has been discarded, breaking my automation block. Now all new timeline items have the created_at timestamp of when the mutation was executed.

This has completely destroyed the point of my automation block which would import historical emails into "Emails & Activities" in monday CRM.

Here's details of the automation block that has been broken:
https://monday-help.dsapps.dev/microsoft-365-office-embedded/import-outlook-emails-into-activities
 

Key benefits of this workflow action (before it broke)

• Exact dates and times of the original emails are retained in each activity
• Emails are added in an idempotent manner – workflow reruns do not add duplicate activities