Cannot filter Document report by Process Group

Currently you can get a report of All Documents in the system but there is no easy way to filter these to high level Process group. You can export to Excel but then the Group column does not list by high level Process group. You have to select each individual lower level folder and these do not list as expected starting with the High level Process group in many cases. Also it is a pain to have to run the whole report BEFORE you can apply the filters at the top.