Hello, I have an external hard drive that use to show up on my iMac (2017 High Sierra), but it has stop showing up. It lights up and I can feel that its on so I know its working. Below are the steps I took to fix it: I tried different usb ports put it doesn't show up. I plugged in my spare WB MyBook drive to see if the USB ports are working, my WB hard drive shows up perfectly fine. I've switch the cables, still doesn't show up. Connect the hard drive to a PC, shows up. Connected the hard drive to an old MacBook and it shows up! I'm completely lost! Why did it stop showing up on my iMac 2017? Help! ps. When I look in Disk Utility I do not see the hard drive.