External Hard Disk Drive Not Showing Under 'Devices' I have just updated my OS to MacOS Sierra. I have connected my external Hard Disk Drive (HDD) and it is not displaying under 'Devices' in my Finder window. It worked fine before the update.

I am using a MacBook Pro With Retina (Late 2013), running MacOS Sierra (Version 10.12). My external HDD is a SeaGate Slim SL Media (500GB).

The external HDD shows up in the Disk Utility application. It also shows up on the About This Mac > System Report > USB. I am not sure what is wrong, the external HDD is identified but does not display for use in the Finder window.

I have read that it could possibly be in sleep mode and putting the MacBook to sleep (whilst connected to the external HDD) and waking it up again should fix the issue. However, this did not work. Nor did restarting my MacBook. It was also mentioned elsewhere that it may require extra power, so I attached the power adaptor to my MacBook and still, no success.

I do not wish to erase the contents of the external HDD.

Is there a way to get my external HDD to be working as expected with my MacBook?

Thank you very much in advance.
The 'Sharing and Permissions' option has been changed to 'Read-Only' for no apparent reason. This has happened to me previously, but it still showed up under 'Devices' in the Finder window.

I believe in the macOS Sierra update, this does not show.

Fix for issue:
Download the Paragon Driver for Mac OS to gain access for Seagate external drives without having to reformat from the following link:

http://www.seagate.com/gb/en/support/downloads/item/ntfs-driver-for-mac-os-master-dl/

Install the Paragon Driver and follow the steps. You will be asked to restart your Mac. Once your Mac has been restarted, the external HDD will display once again under 'Devices'.

Note: This resolution allows you to have access to your external HDD to modify it as you wish. It does not reformat the HDD - so your data is safe.