Hello,
In a Confluence space, under content tools -> export -> PDF custom export. If you UNSELECT all pages and click on EXPORT, it still continues to download all pages. I also looked at the network call that went, all page IDS were put against the key: "contentToBeExcluded" rather than to "contentToBeExported".
If that's not strange enough, the EXPORT progress bar hangs at 99% & just says converting so and so page to PDF.