Thank you for the feedback!
The issue is caused by a rendering bug in the browser. I was able to reproduce it using the current official version of Google Chrome, but not in Google Chrome Beta which means that the issue is already fixed by Blink/WebKit developer team.
As a workaround I can suggest calling kendo.resize at the change event of the Sortable widget which will force the chart to redraw itself. For example:
//redraw the chart
I hope this information will help.
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