POST /api/v2/analytics/query 500 for custom attribute

Stuck on 500 Internal Server Error when querying custom attribute cust_tier via CLI. Provider genesyscloud v1.68.4, Region AU-1. The attribute exists and is populated in the UI. Query JSON validates locally.

POST /api/v2/analytics/query
{
 "data": [
 {
 "id": "cust_tier",
 "type": "attribute"
 }
 ]
}

Response is empty. Is this a known bug or schema mismatch?