Can you access the My Cloud at all from Windows File Explorer? Can you map a Share to Windows File Explorer?
https://support.wdc.com/knowledgebase/answer.aspx?ID=2676
Are you running any third party security, anti virus, or firewall software on the Windows 10 computer? If so have you tried disabling them?
Are you logged into Windows using the main administrator account first used when setting up Windows or as a guest or secondary user that has restricted access?
As a troubleshooting step you could downgrade the SMB to SMB1 per the directions in Windows 10 Specific Method 6 in the Compilation of Windows 10 Methods, Steps and Solutions post to see if there is an SMB issue going on.
