You’ll get a real answer from someone who knows soon, but I’m pretty sure that in the plugin settings there is a place that lets you choose posts, pages and other types.
On the WP Discourse Publishing Settings tab, you need to select both ‘post’ and ‘page’ in the “Post Types to Publish” setting. That setting is found near the bottom of the page.
If you have enabled ‘page’ on this setting and are still not able to publish pages to Discourse and have comments show for them on Discourse, let me know and I’ll look into what is going wrong.