Issue: Thread posts disappearing

Sorry if this has been posted before... I searched the issues using the keywords 'post display' and 'post disappear' and didn't find any relevant threads.

It has happened in every thread I have opened, except the ones with less than 20 posts on the page. When I open a thread, all the posts on a page will load (as seen in screencap #1 of Erendis' contest thread) but then the earliest ones disappear after the page finishes loading (as seen in screencap #2). When taking the screenshots, I didn't scroll at all from when Erendis' post loaded (Post #1 in the thread) to when it and the next few posts disappear, as evidenced by Post #5 appearing right under the thread functions/toolbar. Several minutes after taking screencap #2, I manually refreshed the page (i.e., I pressed F5) and took a new screencap [#3]. More posts disappeared (Post #9 is at the top), which seemingly correlates to the total number of posts on the page; the thread's posts increased from 24 to 28 between screencaps #2 and #3.

As far as I can tell, this only happens on the pages with the newest posts. The older pages of all multi-page threads that I've checked still display without any problems. I've logged out of AF on all my devices (laptop, mobile devices), closed the browser on all devices (or deleted the browser from the multi-task bar), and logged back in to AF on Chrome, but the problem still persists.

Other possibly relevant information: I usually never log out of AF. I use the latest version of Chrome. I have my forum settings display 40 posts per page, and it's been that way for many weeks, if not months. I was logged in and viewing threads at the time the auto-refresh was re-enabled on May 16th (around noon, my time), which was when I first noticed the problem.
Please help!