This could be due to the fact that the window has been rendered off the screen. The desktopAvailableHeight substracts the height of the taskbar from the height of the screen, that is why we used it. Try using the height property to see if that won't create problems. But I must affirm that the desktopAvailableHeight is pragmatic. So please try this code:
x: screen.width - width - 12
y: screen.height - height - 48
Feel free to update the x, y values to the desired figure.