While experimenting with tags, I noticed that filtering by the
no tags option didn’t work as it was not showing any topics when there were topics without any tags.
After some poking, this seems to happen only for admin/moderator accounts (for users it always works fine), and if
allow staff to tag pms = true. I know the option seems to be unrelated, but I reproduced this multiple times in both latest stable and in tests-passed. When the option is off (the default), the filtering by
no tags works fine. But with it on, it seems to break it somehow.