I had a working 1TB My Passport Hard Drive for Mac and it was working fine. I bought a second drive, a 4TB My Passport Hard Drive for Mac and the second disk isn’t seen, even though the light comes on. If I connect the 4TB drive first, it is seen and operates fine, but then adding the known working 1TB drive, that isn’t now seen. Why am I unable to connect two drives to my Mac running High Sierra OS X 10.13.3?
I was going to buy Seagate, so may have to send the 4GB back for a refund as it doesn’t work and buy a Seagate.