Thank you.
Yes, jsreport.Binary.Ph2 seems to work perfectly with Highcharts 6.0.7.
A simple chart in Highcharts 6 seem to be working fine with with phantom 1.9.8. One of the charts causing the error was a stacked column chart. I did not play much with the chart options, so not sure what was really causing the issue.
Anyway with some modification and setting the zoom to 0.75, jsreport.Binary.Ph2 is working great.