See the following post for a workaround to this well known and discussed issue.
https://community.wd.com/t/new-release-firmware-release-04-04-02-105-1-27-2016/148441/68
Eject the USB hard drive via the Dashboard, then remove any extra Share entries for the USB drive in the Dashboard, then reattach the USB hard drive to the My Cloud and rename the USB Share back to its original name without the “_x” appended text.
