"invite user" mutation error and issue

I’m experiencing an inconsistency between GUI functionality and API access for user invitations on my Monday.com account. The invite_users GraphQL mutation returns an “Unauthorized field or type” error, despite being able to successfully invite users through the web interface.

API Request Used
{
“query”: “mutation { invite_users (emails: [“[email protected]”], product: work_management, user_role: GUEST) { errors { message code email } invited_users { id } } }”
}

Complete Error Response
{
“body”: {
“data”: {},
“errors”: [
{
“message”: “Unauthorized field or type”,
“path”: [“invite_users”],
“extensions”: {
“code”: “UNAUTHORIZED_FIELD_OR_TYPE”
}
}
],
“extensions”: {
“request_id”: “33e7a964-6461-9d14-88c5-17fc0daa13de”
}
}
}

Details of my setup:

Plan: Free plan (testing before upgrade)
Scopes granted: users:read, users:write, account:read, boards:read, boards:write, workspaces:read, workspaces:write (and others)
Token: Generated via OAuth, confirmed active

Additional context:

When I perform the same action through the monday.com UI (invite via email), it works fine. The invited user shows up in the users {} query and returns a valid id.
The API, however, always returns the error above.

My questions:

Is the invite_users mutation restricted by plan (e.g. not supported on the Free plan)?
Or is this error expected in the API but not the UI?
If not plan-related, are there additional scopes or permissions needed beyond users:write for this mutation to work?