Conversations API: DROP_PARTICIPANT returns 403 Forbidden

Attempting to eject a participant from an active conference using the endpoint to update a conversation participant’s communication by disconnecting it, with the body { action: "DROP_PARTICIPANT" }. The request fails with a 403 Forbidden, even though the token has conversation:read and conversation:write scopes. Here’s the snippet:

const res = await client.conversations.updateParticipantCommunication(conversationId, participantId, communicationId, {
 action: 'DROP_PARTICIPANT'
});

The user is the conversation initiator. Am I missing a specific permission or is the endpoint deprecated for this use case?