When the Patch Inventory operational rule gets executed, it executes successful. However some times the actual inventory has not been updated. This is actually because the Operational rule just call the inventory Module on the client. Once its able to do that it changes the status successful. This is as per design. Later Inventory module collects and send an inventory. If there is an error occurred, the inventory does not get updated, however the Operational rule still shows as executed successful.
This is not good for the administrator to understand the status on the Inventory collection. There should be some warning to address such scenario.