Observe the tag wiki for the infinite-stratos tag at Anime.SE. As of now, the excerpt reads:
If you try to edit the tag wiki, you'll see that the angle brackets there are literal angle brackets
>, not HTML entities
IS <Infinite Stratos> is a light novel series by Izuru Yumizuru with illustrations by Okiura and CHOCO.
The angle brackets are also displayed correctly in the hover-popup:
However, if you go to the tagged questions page for the infinite-stratos tag, the text
<Infinite Stratos> is missing, presumably eaten by some sort of HTML processor.
Looking at the page source suggests that the problem lies somewhere upstream - the
<p> tag that contains the excerpt text contains the following, without the angle brackets or their contents.
IS is a light novel series by Izuru Yumizuru with illustrations by Okiura and CHOCO.
Changing the literal angle brackets to entities isn't a fix for this problem - if you do that, then the tag wiki displays the entities literally as
> without converting them to