I ran across this the other day when I wanted to copy my Search Ranges files from my old install to a new install on my new Windows 10 laptop.
I have been moving/copying files about getting the new machine setup. At some point copy and paste of files and directories stopped working in Explorer. I could still copy at the Command prompt. It turns out there are a bunch of posts about the web on this on many different operating systems. They range from reboot to checking the file system, system reset and more drastic things. Finally I ran across something helpful. Restart the Windows Explorer service. This is trivially simple to do and if you hit this issue you should probably try this first. Just start up the Task Manager and search for the Windows Explorer process in the Processes tab. On the bottom right there will be a Restart button. Click that. After I did this copy and paste of files was working again.
For reference my Windows version is Windows 10 Home Version 1607 OS Build 14393.1593.