Initially at http://ee-flow.wmflabs.org/wiki/Special:Notifications
I clicked "More..." and it loaded one batch.
I clicked "More..." again, but nothing happened.
I opened web-console, and saw the error message:
"TypeError: mw.echo.overlay.updateCount is not a function"
I then hard-refreshed the page. This time, I was able to load 2 additional batches. After that, nothing happened. The same error message was shown in web-console. (Screenshot)
I then hard-refreshed the page, and all old notifications loaded successfully.