IMX219 Focus with preview code does not display the preview whilst focusing

This is with reference to the code provided to us by Arducam -

in which the a preview window shows the focus in action. Upon running this code we find that the preview window does not pop up even though the focus occurs when the ‘up’ and ‘down’ keys are pressed.

1. Pi zero w
2. Picam with imx 219 (Raspberry Pi Official Camera Module V2 with 8 Megapixel IMX219 Autofocus Replacement)

Software (OS) :
Raspberry Pi OS with desktop
* Release date: October 30th 2021
* Kernel version: 5.10

Have you connected hdmi display? The image is shown on hdmi disply due to it is controled by the GPU.