Analytics API: Grouping by queue AND media type returns empty

Trying to get a breakdown of interactions by queue and media type. The docs say I can nest aggregations, but I’m getting an empty result set.

Using this payload:

{ “aggregations”: [{ “dimension”: “queue.id”, “count”: {} }, { “dimension”: “interaction.mediaType”, “count”: {} }] }

The API returns 200, but the data array is blank. Is this a valid structure or do I need to use a different endpoint for multi-dimensional grouping?