No usb device found when trying to network map on Mycloud

i just bought 3tb my cloud and cant access any hard drive I plug into the back of the unit. I tried network map the drive but no usb hard drive shows up. the usb drive will work in windows. Im beginner so don’t know any Linux or anything. I tried looking all over so answers and called support they think there is defect in unit but the port has to work because my external hard drive is usb powered and runs when plugged into the my cloud. ANY HELP WOULD BE GREAT!!

When you connect your USB drive to the back of the My Cloud does the USB Icon within the My Cloud Dashboard indicate a USB drive is attached? Does the WD My Cloud Dashboard Alert/Notification icon indicate the USB drive could not be mounted or indicate some other sort of error?

If the USB drive is seen by the My Cloud but does not get mounted (ie no Share appears on the Share page) see the following threads for more discussion.