3 weeks ago
I noticed you said your reports are kept for 60 days. This means that any reports run within the last 2 months will be kept (these are final reports).
You're trying to generate a new report that covers a date 3 weeks ago, this would require the Historical Data Retention setting for Client associations to be >= 21 days and Inactive client to be >= 21 days for that report to complete. Please check your HDR values to ensure you're running a report on data that hasn't been aged out.
Senior QA Engineer - Network Services
Aruba Networks, a Hewlett Packard Enterprise Company