When you open a flow board it loads a maximum number of topics. If there are more topics on the board, when the user scrolls down to the bottom of the page they're loaded dynamically.
This has stopped working.
Example: https://www.mediawiki.org/wiki/Project:Support_desk
When reaching the end of the page, a "loading" image or text (I don't remember) appeared and more flow topics were loaded, but it doesn't seem to do nothing now... nor even a request to the server (looking at the browser's console). No JavaScript errors found in the browser's console.
Tested on Firefox and Chrome.