I'm on 10.6.8 with the latest update and iTunes 10.4 and yes, View Options is set to show the preview. Looks like Apple broke this somehow.

Here's one report of someone having the same issue:
https://discussions.apple.com/thread/3214138" onclick="window.open(this.href);return false;
Oops... just found another and definite bug in latest iTunes... argh!!!
https://discussions.apple.com/thread/3201322" onclick="window.open(this.href);return false;