Dunno, for me, moving my fingers to the keyboard to do Ctrl-C and Ctrl-V is way faster than right-mouse-button clicking, tediously moving to select the appropriate menu option, and clicking again.
I watch so many people copying and pasting with the mouse and every single stinkin' time it's soooooooooo much slower than if they used the keys.
As long as a windows app conforms to the Cntrl c -Cntrl V convention there should be no problem with the app.
The issue with menu dropdowns is that it (key and mouse press) has to be specifically written into the app, and has to follow the focus of the selected open window, which can be tricky in a complex app. Maybe this was an oversight by the code writers in this case, then again maybe not.
Keyboard shortcuts rule!