This is a problem I'm seen primarily with new users.
Questions and answers are entered which sometimes use the < > angle bracket characters for emphasis, URLs (e.g.
http://<server>/site), poorly formatted code or occasionally ASCII art. As a result what's been entered is not displayed and makes little or no sense. (Unfortunately this isn't noticed by them or most answerers.)
Is it possible that unless the angle brackets contain an allowed HTML tag that they are simply HTML encoded instead so they still display?