Participant attributes from Web Messaging missing in Architect Inbound Message flow

We’re routing inbound web messages through a custom DFO channel. The client is sending custom attributes via the Web Messaging SDK, specifically customerTier and priorityScore. I can see these attributes populating correctly in the Genesys Cloud UI when I inspect the active conversation.

The issue surfaces in the Architect flow. I’m using a Data Action to fetch the conversation details to expose these attributes to subsequent routing logic. Here’s the JSON payload I’m sending to the fetchConversation endpoint:

{
 "conversationId": "{{conversation.id}}",
 "includeParticipants": true
}

The response returns the participant object, but the attributes field is completely empty. It looks like this:

{
 "participants": [
 {
 "id": "12345",
 "name": "Web User",
 "attributes": {}, 
 "state": "connected"
 }
 ]
}

I’ve verified that the attributes are set on the participant level, not the conversation level. When I check the raw API response from /api/v2/conversations/webmessaging/{{id}}, the attributes are there. But inside the Architect Data Action, they’re gone.

Is there a specific flag I need to set in the Data Action config to pull participant-level metadata? Or is this a known limitation with how DFO channels map SDK attributes to the internal participant object during routing? I’ve tried adding expand=attributes to the query params, but that throws a 400 bad request.