My passport for mac (on my imac) icon no longer appears on my desktop, nor can Time machine find it, disk utility is of no avail. It has simply disappeared.
You can update the BIOS of the PC the USB hub is connected to prior to connecting the WD USB 3.0 hard drive. Depending on the manufacturer of the BIOS and the USB hub this may be required for the USB 3.0 hub to function correctly.
In order to fix this issue, update the firmware for the USB 3.0 Hub’s controller. Most USB 3.0 Hubs’ controllers are manufactured by Via Labs, and updates and instructions can be found and downloaded from the Via Labs website.
Also you can follow some KBA mentioned below-