Thanks, I've explored that. I have a triple screen and am used to things moving off into the void, but if anything it should have gone to the right-hand screen.
A VBA snippet to move it to center-screen would be appreciated (I know just enough to hack one together, but I'm sure it can be done in seconds by someone more skilled). I am going to try moving my virtual screen around to see if I can catch it, sort of fishing in the dark...
ETA: and, nope. Fished all around in screen space and no sign of the pane.