Missing keyboard shortcut in El Capitan 10.11.5 to switch between windows within app I've just started running El Capitan (10.11.5) and one of my favorite keyboard shortcuts seems to have disappeared: the keyboard shortcut that let you move between windows within the same application. It used to be  Cmd ⌘   `   (tilde) but now that shortcut doesn't work and I can't figure out how to get it back. 

Any ideas? Thank you in advance.
The Keyboard item in System Preferences has a Shortcuts tab. The Keyboard item in the Shortcuts tab has one item labeled Move focus to next window. The binding for that has a  `   rather than a  ~   (with the  Cmd ⌘  key; I don't know how to type a cloverleaf), but either binding has the same effect for me (that box is checked on my Mac).

It's possible you simply need to check that box; in any case, that seems like the first place to look.