When using the DistillerSR API, the POST Query method is used to retrieve the information from your saved report in Datarama. It will only work if your Datarama report contains response sets.
Using the endpoint https://v1serv-prod.evidencepartners.com/api/v1/datarama/query , if you call this method and receive "[ ]" as a response, it means your report includes only Tags (reference fields), and no response set data from submitted Forms.
In order for this API method to work, you need to have at least one response set included in your saved report.
More information can be found in the DistillerSR API documentation.