Ensure that you're using the latest Remote Desktop Connection 7.0 client update.
Even if you're using the latest version, re-installing the RDP client and rebooting might help.
Verify that rdpclip.exe is in its right place :
Also verify that the registry key
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Terminal Server\Wds\rdpwd contains the right entry for
StartupPrograms. It should contain "rdpclip", but you can also try the full path "C:\Windows\System32\rdpclip.exe".
The last-ditch solution, used when no better one is found, is to use a .bat file that contains:
Taskkill.exe /im rdpclip.exe
Some people even added this script as a startup item, and report that this solved the problem (after reboot).