Came across this and tried it out in the client environment. So far so good. I’ll keep you posted.

Fix for Cannont Empty the Clipboard in Office

Method 3:

If you’ve been using Remote Desktop, you may get the cannot copy to clipboard error because Remote Desktop uses the clipboard and it can cause weird issues with Excel.

Go to Task Manager and then click on the Processes tab and kill the process called rdpclip.exe and see if that fixes your problem! If you have UltraVNC installed, it may also be the culprit! Any kind of remote desktopsoftware could be causing the issue, so make sure to check to see if you have the problem when one of those programs are running.