PATCH /conversations/calls/{id}/participants/{id} 400: OTel trace context lost in participant attributes

We’re injecting OpenTelemetry trace IDs into participant attributes during live calls for distributed tracing. The initial GET returns the attributes correctly, but when we PATCH them back after an external API call, we get a 400 Bad Request.

{
 "code": "bad_request",
 "message": "Invalid attribute format"
}

The trace context is a 64-char hex string. Is there a length limit or special character restriction on participant attributes? Here’s the payload we’re sending: