LJ amnesia?

[hmpf]

Is there something wrong with LJ filters lately, or perhaps in general? I don't usually use them, so I don't have sufficient data to really judge, but it seems to me they're unreliable. I made a few filters for a test, a while ago, and then sort of forgot about them. However, I just noticed that the 'everything but Doctor Who' filter I made yesterday night seems to have disappeared completely, so I checked my older filters again and noticed that for at least some of those, no posts at all will show up. So, is this something that frequently happens if you use filters? LJ completely forgetting a filter you made, or not showing you any of the posts that should be in that filter? I seem to remember noticing something like that back when I did my original filter experiment - I think it was one of the reasons why I never really used filters after that experimental phase - but I'm not quite sure. Comments from more filter-experienced users would be welcome...