But I wanted to say that I had the same issue and the reason why was because I had locked down the site behind HTTP Basic Authentication (a simple username and password).
I guess the PDFs use linked images, and that’s why it won’t work under a restricted site.
If they used embedded images, then I believe it would work.
That is correct - one of the reasons why images might not be displayed in the PDF is if the Dashboard site is behind a HTTP Basic Auth.
If the user wants to continue using HTTP Basic Auth type of protection for the Dashboard, we recommend using our Dashboard Lock extension: https://mainwp.com/extension/dashboard-lock/
The Login Lock feature of the extension is pretty much the same as classic HTTP Auth, but we have added some exceptions so that it would not interfere with MainWP functionality.
Another possibility we’ve seen is that the site has an issue with mixed content. So, if the URL of the image is http:// but the site has a certificate, the image might not be displayed in the PDF.