Passing CRM ID via Web Messaging SDK startChat() for New Relic correlation

Here’s the initialization block I’m using to start the chat session:

const guest = new genesyscloud.webmessaging.Guest();
guest.startChat({
 attributes: {
 "crmId": "CUST-998877",
 "channel": "web"
 },
 callback: function(err, chatId) {
 if (err) console.error("Chat failed:", err);
 else console.log("Chat started:", chatId);
 }
});

The chat connects fine, but when I pull the transcript via the /api/v2/conversations/messaging/conversations endpoint later, the attributes object is empty. The CRM ID isn’t sticking to the session metadata. I need this value to correlate the chat transcript with our New Relic custom events for latency tracking.

I’ve checked the docs and it says custom attributes should be supported in startChat. Is there a specific schema requirement for the keys? Or does the Web Messaging SDK strip non-standard attributes before sending them to the platform? I’m using SDK version 2.4.1.

Any ideas on why the data drops off?