Вы можете установить maskBullets
в значение false на экземпляре диаграммы, чтобы предотвратить его обрезание LabelBullet, например, chart.maskBullets = false;
Демо:
// Create chart instance
var chart = am4core.create("chartdiv", am4charts.XYChart);
// Add data
chart.data = [{
"date": new Date(2018, 3, 20),
"value": 90
}, {
"date": new Date(2018, 3, 21),
"value": 102
}, {
"date": new Date(2018, 3, 22),
"value": 65
}, {
"date": new Date(2018, 3, 23),
"value": 62
}, {
"date": new Date(2018, 3, 24),
"value": 55
}, {
"date": new Date(2018, 3, 25),
"value": 81
}];
chart.maskBullets = false;
// Create axes
var dateAxis = chart.xAxes.push(new am4charts.DateAxis());
// Create value axis
var valueAxis = chart.yAxes.push(new am4charts.ValueAxis());
// Create series
var lineSeries = chart.series.push(new am4charts.LineSeries());
lineSeries.dataFields.valueY = "value";
lineSeries.dataFields.dateX = "date";
lineSeries.name = "Sales";
lineSeries.strokeWidth = 3;
// Add simple bullet
var circleBullet = lineSeries.bullets.push(new am4charts.CircleBullet());
circleBullet.circle.stroke = am4core.color("#fff");
circleBullet.circle.strokeWidth = 2;
var labelBullet = lineSeries.bullets.push(new am4charts.LabelBullet());
labelBullet.label.text = "{value}";
labelBullet.label.dy = 20;
<script src="//www.amcharts.com/lib/4/core.js"></script>
<script src="//www.amcharts.com/lib/4/charts.js"></script>
<div id="chartdiv" style="width: 100%; height: 300px;"></div>