Tried with default theme:
Tried with all other plugins disabled:
Page showing the issue: https://nextgenthemes.com/#lightbox
This is even happening on your main site’s Lightbox example. When you use the lightbox or link to lightbox the iphone user can’t play the video. They click on the lazyloaded player and the popup is just a blackbox with a loading circle that never stops. I have tested this on multiple iphones in chrome with the same issues. No issues on my Samsung thought.