Chrome seems not to display elements in inline svg. Here is an example (code below or view it at http://www.bobwyttenbach.com/chromeuse.html):
I spent a long time debugging inline svg use elements not showing up. The chrome bug discussed by BobW seems fixed at this time. To eliminate the same issue caused by something else entirely, try commenting out the tag from your HTML.
Of course, this will likely break every relative link on your site, but the elements now show up. One step forward, half a step back :)
Related info here: Using base tag on a page that contains SVG marker elements fails to render marker