Open in new tab with [print_link]

Only thing I can think of if you are using a caching plugin?

I just tested on my test site https://lesterchan.net/wordpress/ and it works fine for me.

no caching plugins in use yet. The site is in development.
Print This Page link on bottom of the page at the url
https://66.201.98.72/~promusica/

“Forbidden – Visitors from your country are not permitted to browse this site.”

Here is my options page https://imgur.com/iI7i6vr.

I am using <?php print_link(); ?> to display the print link.

I would suggest witch to the default theme to test.

Another thing I can guess is that some JS in some plugins/theme is hijacking the onclick event.

You were right, WP Accessibility was stripping target attributes from links