Hi Case, In latest trunk Purchases by Organization Reports are working. Not sure that this is your case, but if you create purchase order w/o supplier party, and then use change party and add a supplier to the order, the order will be created w/o BILL_FROM_VENDOR role. And these orders are not shown in Purchases by Organization Report. In rev629396 i fixed this bug.
Some entities (probably OrderReportPurchasesGroupByProduct entity too) cannot be viewed from webtools. Bilgin
