If you configure Remote FX USB redirection (Local Group Policy Editor > Administrative Templates > Windows Components > Remote Desktop Services > Remote Desktop Connection Client > Remote FX USB Device Reditrection > "Allow RDP redirection of other supported RemoteFX USB devices from this computer" = Enabled,) Then, open RDP and uncheck the box for Printer redirect, check the Remote FX USB printer, (Show Options > Local Resources > Uncheck 'Printers' > Click More > Expand Other supported RemoteFX USB devices > check the USB scanner) and THEN connect to RDP, the redirected printer will now have scan options, but GP still does nothing when you click Scan.