jQuery Countdown Timer not showing - works in preview

I have added a html webpage with the jQuery Countdown Timer to the layout.
HTML page is hosted locally on the Xibo server.
jQuery Countdown : https://codepen.io/piotrswioklo/pen/fqnIA

When i preview the layout it displays the countdown, however on the client (Windows) it displays “NaN NaN NanN NaN” instead of days, hours, min & seconds. [Screenshot attached]

On Windows Clients:


Any help on this will be much appreciated, thank you.