It didn't work in previous versions either

Which version are you referring to?

Which browser are you using?

Access to the browser clipboard for cut, copy and paste operations is restricted by the browser, and IE will give a prompt as to whether access should be allowed. If access has been denied, then the buttons will fail to work in IE11, as it unfortunately does not appear to correctly report this change.

You should use CTRL + C and CTRL + V for Cut and Copy operations instead, and in Editor Profiles -> Plugin Parameters -> Clipboard, set Use Paste Dialog to Yes.