With Ribbons enabled, I tried some routine copy and paste actions using the icons in the Keywords panel. Nothing was copied or pasted. I switched back to the interface without Ribbons and the process worked correctly.
Copy & Paste error (no pun intended) and sloppy testing.
The Keywords Panel uses different command is for copy & paste and I've missed than while copying code over from the Metadata Panel. Fixed for the next release.
:)