I can’t reproduce the problem here. So, let’s try the following. Please have a look at the one minute clip below (you might download it, for a better handling/quality)
I have pulled the sub menu out, so the copy command should show its result (that there is something) when the paste is not longer grayed out, Which is your problem here, I understand, but the visible menu will give you much faster feedback, when finally something has been copied.
Please start with a fresh new scene, can you reproduce this small example?
If not, please share the scene file of your set up of that specific scene, and I will take a look into it.
All the best