a question about LJ tags

In general I like and appreciate the tag feature. It certainly makes it easier to catch up with just specific posts after a longer absence, if someone uses them, and is easier than using the memory function, if I want to read all posts related to a tag, not just one specific post. What puzzles me however is, how some people use tags consisting of several words with spaces inbetween, and those don't work for me, no matter which journal I try to click on one of those. When experimenting with tags in my LJ I also noticed that there is no problem creating and assigning such tags, but they won't work afterwards. The tag will link to an URL of the type ".../tag/word1+word2" and I get an error page "Sorry, one or more specified tags do not exist." Is this a temporary bug and these multiple word tags did work at some point? Is it just me and they work for other people? Or have people who assign these tags just never tried to use them, and are unaware of the tags malfunctioning?