Is there a way to configure a template to force all data to be retrieved first prior to generating the report?
Yes.
If you are using relationship handlers to retrieve data on-demand as the user expands nodes in the instance list, your report will only contain rows that have been retrieved from the server.
To configure a template to force all data to be retrieved first prior to generating the report, you need to create a ‘configuration’ sheet in your template. A configuration sheet is a special sheet called ‘<#Config>’ that contains report settings. This sheet will not be included in the final report. Set the property ForceRetrieveAllData to True by putting the text ForceRetrieveAllData in column A1 and text True in column B1.