The behavior is designed such that zooming is limited upto a certain region so that the user doesn’t end up zooming into a blank region (region with no dataPoints). To zoom into a certain region, there should be a minimum of 3-4 dataPoints over the axis.
In your case, the zoom doesn’t work as there are less than 3-4 dataPoints with different values over the axisY for the given dataSeries. We suggest you set the zoomType to x in such scenarios.
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Indranil Deo
Team CanvasJS