Thanks for reporting this. As of yesterday we’ve merged an update that is intended to make post navigation via heading more reliable. We’ve ensured consistent headings are available for every post, and have added headings with live regions that will announce when additional posts are being loaded.
This update is currently live on meta.discourse.org, as well as your site on our hosting (and any other Discourse sites that update going forward).
Let us know if encounter any more issues with this!