This seems to have started either when I upgraded to Monterey 12.3.1 or Safari 15.4. The images from a web site show when I'm in Reader mode in Safari, but only blank areas are shown for the images when I attempt to print.
iMac 27″, macOS 12.3
A possible workaround: have you tried the Save as PDF option and then print the PDF from Preview app?
Enable Develop menu and make sure that Disable Images is not enabled:
Use the developer tools in the Develop menu in Safari on Mac - Apple Support
I'm running out of ideas. The same macOS/Safari versions work here as expected.
Does this happens on every website or is it something specific?
A Guest user experiences the same issue?
Have you tried to reset user's Safari preferences (quit Safari and move them somewhere – do not delete them, keep them as a backup)?
If I try to Save as PDF after I select the Reader option in Safari for the web page of interest, the images are not included, even though I can see them in the browser.
I tried that before. No change, still doesn't include images.
For your information: I've just seen a new thread addressing the same issue.
Safari Reader not printing images - Apple Community
Safari Reader still not printing images
