I do not have a keybinding conflict, in fact both Cmd+Shift+Z and Cmd+Y work!!
I am flabbergasted: I tried Cmd+Y (I was not aware of Cmd+Shift+Z) so many times and it never worked, so today I got fed up and decided to put in the request, which can now be closed.
Many thanks for making me check it out again. I’m a real idiot.