Analytics API returning empty data for 30-min intervals

Trying to pull agent utilization metrics like tHandle and tAcw broken down by 30-minute intervals. The standard query works for daily aggregates, but when I switch the interval parameter to PT30M, the response comes back empty. No errors, just zero records. Here is the endpoint I’m hitting:

GET /api/v2/analytics/queues/summary?dateFrom=2024-05-01T13:00:00.000Z&interval=PT30M&metrics=tHandle,tAcw

Is PT30M not supported for queue summaries or do I need a different report type?