If we take a Next.js (React framework) site, like this one: https://spencerwoo.com/blog/revisiting-blogging-with-notion-2022, the Preview and "Permanent Copy" fail to contain any content, but the "Web" view (which as I understand it just IFrames the site) works without fail.
Expected result (1st image – "Web" view), problematic results (2nd image – "Preview" view) and (3rd image – "Permanent Copy" view – this is from another post on the same site that has time to make a permanent copy, but I anticipate the same problem).
For context, this is a Notion-powered Next.js site, so it's possible there's some quirks with cross-site permissions, but I imagine this isn't the case since the main thing that changes (I think) between "Permanent Copy/Preview" and "Web" is the
presentation (and otherwise things that make it clear a crawler is present vs human).