Updating participant attributes mid-call via PATCH /conversations/calls/{id}/participants

Docs state: “You can update participant information during an active conversation by sending a PATCH request to the participants resource.” I’m trying to push custom attributes to a participant object while a call is live. The goal is to tag the interaction for downstream analytics without ending the session.

Here’s the setup:

  • Using Python requests with a valid bearer token from client credentials flow.
  • Endpoint: PATCH /api/v2/conversations/calls/{callId}/participants/{participantId}
  • Payload:
{
 "attributes": {
 "campaignId": "12345",
 "source": "webchat"
 }
}

The response is a 200 OK, which is good. But when I immediately GET the participant, the attributes are missing. I’ve checked the token scope and it includes conversations:write. The call is definitely active and the participant IDs match. I’ve tried adding application/json headers explicitly. The SDK method conversations_api.patch_conversations_participants behaves the same way. Is there a delay in propagation or am I missing a required field in the patch body? The docs don’t mention a specific delay for attribute sync.