The OOTB status report is using data in the Data Warehouse. Given that your PM's are 'completing tasks right before creating the report', the Data Warehouse may not have been refreshed, prior to running the report. Either run "Load Data Warehouse" more regularly (try in non-prod environment first), or, create a custom version of the status report pointed the live data (eg using Data Source CA PPM BEAN). I generally go with the second option.