Nintendo regularly changes encryption keys. Many older versions of USB Helper stopped receiving new keys when their key servers went offline. The "Upd" (Update) versions of tools try to fix this by using new ticket sources or community key databases (like the Title Keys site ).
The tool was "empty" without a database of keys. title keys for wii u usb helper upd
The software will then download the database. This may take a few minutes depending on your internet speed. Nintendo regularly changes encryption keys
If the GUI method fails, use the brute force method: title keys for wii u usb helper upd
Download the USBHelperLauncher from GitHub. This patches the app at runtime to bypass "discontinued" errors.