Your problem seems similar to the problem another user is experiencing in this thread: Using MyCloud as iTunes library
Do you see the My Cloud listed under “Computer” when click on Network with Windows File Explorer?
Quite a few people are having trouble with Windows 10 and the My Cloud. The My Cloud not showing up under Computer in Windows File Explorer is one such problem. It could be iTunes, because of this Windows 10 issue, may not be able to access the My Cloud properly. The following thread lists several methods others have used to solve their Windows 10 problems.
https://community.wd.com/t/compilation-of-windows-10-methods-steps-and-solutions/142576
