Cause
The highlight target is neither communication_channel with channel_id nor communication_publication with external_id. A survey target does not exist in this API.
What to do
Fix the target or send a standalone highlight without target.
application/problem+json
{
"type": "https://masnet.com/developers/errors/invalid_target",
"title": "Invalid target",
"status": 422,
"detail": "...",
"code": "invalid_target",
"correlation_id": "..."
}