Issue with Empty From.User Property in Microsoft Graph API Chat Messages

Issue Summary:

I’m working with the Microsoft Graph API to retrieve chat messages, and I’m encountering an issue where the From.User property is consistently empty. Despite having the necessary permissions (User.Read.All and Chat.Read.All), the API response does not include the expected user information in the From.User field.

Details:

• API Permissions: User.Read.All, Chat.Read.All
• Endpoint: Retrieving chat messages using Get-MgChatMessage
• Observed Behavior: The From.User property is always empty, with both DisplayName and Id fields returning null.
• Steps Taken:
  • Verified API permissions.
  • Inspected the raw JSON response, which also shows empty From.User fields.
  • Checked the Microsoft Graph API documentation for any notes on this behavior.

Example Response:

{
    "From": {
        "Application": {
            "DisplayName": null,
            "Id": null
        },
        "Device": {
            "DisplayName": null,
            "Id": null
        },
        "User": {
            "DisplayName": null,
            "Id": null
        }
    },
    "CreatedDateTime": "2024-09-24T15:11:50Z",
    "Id": "1727190710868",
    "Body": {
        "Content": "<systemEventMessage/>",
        "ContentType": "html"
    }
}

Has anyone encountered a similar issue or can provide insights on why the From.User property might not be populated?

Thanks