pxRetrieveReportData is ootb activity but it doesn’t take count #parameter .
Steps to solve issue
1. Open the report by passing the class and the name parameters using Obj-Open step.
2. Set the property .pyUI.pyMaxRecords of the context page used in previous step.
3. Call pxRetrieveReportData #activity to get the report results.
#ReportDefinition