Since updating to macOS Sierra, my Seagate 1TB Harddrive isn't being read or mounted by my Retina MacBook Pro (2014) ... It appears in Disk Utility but not in Finder or on the Desktop ... In Disk Utility I cannot do anything but format it which I DO NOT want to do .. Any suggestions or help?!
Same here, all drives appear on the bus in the system, but only the seagate mounts. Terrible part, the missing drives are my Time Machine and Downloads. Ugh. So literally, I cant update my apps, use iTunes, backup my machine, etc. I'm thinking about rolling out of the beta.
None of the HD I would like to connect to this Mac have a Thunderbolt connection but that is helpful if the hard drive you would like to connect have that connector.
Yes, USB Sticks seem to work fine, I had a crash from connecting one stick and the Mac rebooted but they mount.
My WD external hard drive will not mount and does not show up anywhere. I also can't go back to an older OS because my backup is on my external HD. All my files are on external HD so iTunes is useless and everything else. I hope they fix this soon.