With offline exporting, html elements in the chart are visible in the exported images.
HTML elements are not visible.
Tested in Chrome 54
Thanks for reporting. We'll take a look as soon as possible.
Fixed #5985, issue with allowHTML in offline exporting.
Neither canvas/CanVG nor svg2pdf support foreignObject and HTML rendering, so we have to fall back to online export for PNG, JPEG and PDF export. SVG support should now work, however, and it falls back gracefully for the other output types.