Please help on page with fullscreen iframe

Hi, so my client wants me to use an iframe to display an external content. They want it so that when I click on a side menu item, it would show a page with a fullscreen iframe. The iframe content showed with no problems in ionic serve and ionic run android -l -c but when I actually compiled it and installed it on both android and iOS phones, it’s blank.

I tried using the whitelist plugin but I think I’m doing it wrong. Please help. Thanks in advance.