@nguoikhivohinh,
In the above code snippet, indexLabels are skipped when there is limited space available for the indexLabels to display or when they get too close to other indexLabels (to avoid overlapping) – this behavior is by design. By changing startAngle by few values, it’s possible to display more indexLabels. Please take a look at this updated JSFiddle.
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Indranil Deo,
Team CanvasJS
