title: highcharts with lots of data render blank in pdf use wicked_pdf
body: <p>wicked_pdf render highcharts well in pdf when you disable the follow options:</p>
  <p>enableMouseTracking: false, shadow: false, animation: false</p>
  <p>But recently I encount a problem: when the stacked and grouped column with a little more data, it render blank in pdf. (Same charts with a little data render ok in pdf!)</p>
  <p>The normal chart:
  <img src="https://i.stack.imgur.com/3SJNc.png" alt="enter image description here" /></p>
  <p>The charts in pdf:
  <img src="https://i.stack.imgur.com/WiAle.png" alt="enter image description here" /></p>
  <p>Anyone can help? Thanks in advance!</p>