If your site contains JS errors, the tooltip may not appear as it should and you will receive upon hover-over an “undefined” value in the Tooltips, or alternatively, no Tooltip will show at all.
To fix this problem, use your web console in FireFox, where you can right-click and choose “inspect element”.
When the console opens, select the Web Console and under JS you will see what JS errors you have. These need to be fixed before the Tooltip will work
To see the JS error console in the Chrome press the CTRL + SHIFT+ C key combination while on the page and the Developers console should show up.