标题属性不适用于Safari上的SVG Rect

I have an SVG created with d3 that has title attributes set on all of the rects for tooltip popups. The code works fine in Firefox, but the tooltips don't show up in Safari--neither Mac or Windows. I know the title attribute is being properly set as I can see it in the Safari Web Inspector.I have an SVG created with d3 that has title at