try fix the function calculateXLabelRotation in chart.js
calculateXLabelRotation : function(){
...
//↓↓↓
this.xLabelRotation = 0;
//↑↑↑
if (this.xLabelRotation > 0){
this.endPoint -= Math.sin(toRadians(this.xLabelRotation))*originalLabelWidth + 3;
}
...
},