POST /conversations/{id}/participants/{participantId}/disconnect returns 400

Trying to drop a single agent from a conference call using POST /api/v2/conversations/{id}/participants/{participantId}/disconnect. The body is empty as per docs, but it keeps returning 400 Bad Request with message “Invalid request body”. Checked the participant ID and it’s definitely the agent, not the customer. Here’s the curl I’m running:

curl -X POST https://api-us-1.cxone.com/api/v2/conversations/12345/participants/67890/disconnect
-H “Authorization: Bearer $TOKEN”
-H “Content-Type: application/json”

Why is it rejecting an empty body?