You can try the manual grab to see if it hiding off screen.
Make it active, then alt and space together, then m, then tap any arrow key and finally move the mouse around without clicking and see if the dialog comes into view.
You can try the manual grab to see if it hiding off screen.
Make it active, then alt and space together, then m, then tap any arrow key and finally move the mouse around without clicking and see if the dialog comes into view.