I have already tried keyboard swapping, no difference / no change... I am familiar with how the action should be performed eg: simultaneous holding of keys, or press and hold Ctrl key, Shift key and then the X key until all keys have been pressed.. I am new to the forum, but I have enjoyed using Paint.net for 15 YEARS.
BTW the command works when selected under the image tab, and Ctrl, Shift, C, still copies a selection and I can paste that.
Just miss having the hot-key(s) shortcut ability for cropping to selection.