Can't see camera's 'passepartout' / overlay around the camera's view I have 'passepartout' selected in the Camera tab.

I have "Lock Camera to View" deselected in View (in the "N" tools section). 

Yet I don't get a passepartout in Camera Perspective.

What am I doing wrong?
Thanks to Leander, I discovered it was offscreen.  I used to scroll wheel to scroll out (way, way out), and there it was.