Hey there again, desktopbrett!
I'd strongly recommend you to try testing the external using its manufacturer's diagnostic tool, now that you got the drive detected in the system. You should be able to find this utility on their official website and it will allow you to determine the health and SMART status of the HDD.
There is a very high possibility that it's faulty, so I'd suggest you to consider consulting with a professional data recovery service.
Keep us posted, though.
SuperSoph_WD