The https://asciidoctor.org/docs/user-manual/ seems straight forward and with the methods stated there (asciidoctor -a allow-uri-read filename.adoc) I still get the same outcome for both. (safe mode was set to UNSECURE)
Could you help me figure out how to include files/web pages in my doc?
Release 0.30.41 of the plugin will be available later today to fix this issue.
In order have the include rendered in the preview, go to "Settings | Languages & Frameworks | AsciiDoc | Attributes" and add the attribute with he key "allow-uri-read". The "Apply" button will activate once you leave the focus of the attribute editing window.
As long as you don't add the attribute, the include will be shown as a link instead.