It seems there are problems with the browser's native user agent string, which is currently (on my system):
Mozilla/5.0 (Windows NT 10.0; WOW64; rv:3.0) Goanna/20170302 PaleMoon/27.1.2
For example, drop-down arrows are missing and categories like Quick Links are being un-grouped. I am guessing the lack of the "Gecko" or "Firefox" words are causing some confusion to the forum.
Switching to the browser's default "Gecko-compatibility" string below solves the issue, but reveals that some nasty
user-agent sniffing is probably going on.
Mozilla/5.0 (Windows NT 10.0; WOW64; rv:3.0) Gecko/20100101 Goanna/20170302 PaleMoon/27.1.2