If the images are not publicly available, they will be not be included in the PDF. Some systems like Cloudflare can also block PrintFriendly from accessing the images.

Solutions

Grant Access To PrintFriendly

In many systems, access to images can be granted based on User Agent. The User agent we use is:

Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.81 Safari/537.36 PrintFriendly.com

Enable Image Encoding

If you are a pro customer, set Plugin Settings → Pro Exclusive Features → Encode Images to Yes.

Keep in mind that this will slow down PDF generation, especially on image-heavy pages.