asus seagate usb sleep mode

Hi, Just discovering my ASUS AC2900 and trying to make it used as a simple NAS. Latest official firmware: 3.0.0.4.384_81351 In Administration/System: "Enable HDD Hibernation" is set to "No" "USB mode" is set to "USB 3.0" I have attached a 2Tb Seagate Expansion Desktop Drive using USB 3.0...