LJ is at it again. They've introduced a new OPT-OUT 'Spam Protection' feature, which is actually a new privacy setting (found here: http://www.livejournal.com/manage/settings/?cat=privacy ). It automagically screens comments containing links onto a special 'suspicious comment' page if the link is to a site that is not on their unpublicized whitelist*.
The user who made the original post cannot see these hidden comments and receives no notification that they exist. Only moderators/maintainers can see these hidden comments, BUT! no notifications are sent to inform mods of the screening. Also, it's been active about two weeks, and it's still buggy as all hell, so if you're a mod, you need to go to each of your comms and check each post to see if any comments have been auto-screened.
As an added bonus, if you have custom comment pages in your comm, you probably won't be able to see the 'suspicious comment' link even then. I ended up appending ?format=light to the url of each post in bloodclaim to hunt down the comments that had been dropped into lj's nifty little oubliette without warning.
NB: The '# suspicious comments' link is only visible if there are suspicious comments, so don't worry if you don't see the link on lj's default comment page layout, or in ?format=light mode, it just means there are none. Yay?
The setting applies to personal journals as well as communities, but this is a post about how it affects communities and their mods.
To turn it off, uncheck the ticky box for 'Spam Protection: Comments containing a link to a non-whitelisted domain will be marked as spam and moved to a special section.' and then click 'Save' at the bottom of the page.
LJ are still working on 'improving' the whole mess, so I have no idea how long this post will remain accurate, but with the way it's working right now, it's not fit for use in any community.
* There is a copy of a whitelist available, http://www.livejournal.com/community/whitelist.bml?authas=COMMNAME, but that, apparently, is a different whitelist, set up for posts in moderated communities, and not for comments at all. (Or so it is writ, somewhere in the depths of the comments on the latest news post.)