When I first installed Win 10 on this originally Win 7 machine, I had to do alot of troubleshooting.
One problem I didn't run into but read about was that folks were having an issue where their Win 10 install did not recognize their Western Digital external drives when the drives were connected to a USB 3 port. Their issue was resolved when they connected to a USB 2 port instead. As voltronic mentioned, you might give another port a try.
Another avenue you can follow is go back to the microsoft compatibility check and see if anything installed on your machine is possibly causing an issue.
Sounds weird but when I first installed Win 10, there were no incompatibility issues found. However, the system was very unstable. About a month after my install and many crashes and manual shutdowns, microsoft reported that the Netgear Genie software was found to be incompatible. I uninstalled that software and have not had an issue since.