Sort of loads, but blank

I’ve uploaded some magazines to my site and linked the pdfs to flipbook and added the shortcodes to posts – when I click on the post I can see a ‘shadow’ of a page turning but there is no content and only a left arrow – which goes nowhere. Can you suggest with the flipbooks won’t render? Here is a page of links – https://pathfinderinternational.co.uk/magazines/ – the posts are behind a paywall but it’s the same result whether logged in or not.

The page I need help with: [log in to see the link]