Here and on my own XenForo the description of a forum is visible under the title, and not as a tooltip. This problem appears an Chrome 32.0.1700.107 m and Opera 19.0. On Firefox 27.0 and Internet Explorer 11.0.9600.16476 the description is shown as a popup.
Examples on XenForo.com:
Chrome and Opera
The weird thing is, that the most users can see these popups on Chrome, but not me. Even after a new installation of Chrome theses tooltips doesn't work.
I was looking for a solution, but found none. So I hope you can help me with this problem. Maybe there is an option in the browser which needs to be active to show these tooltips?