[Solved]-DataLabels formatter not working in Highcharts Sankey Diagram-Highcharts

I was having the same issues. Sankey is really hard to implement I guess. Use nodeFormatter instead, formatter is just not working. Example below.

nodeFormatter: function (arg) {
    if (!this.point.sum) {
        return null;
    } else {
        return this.key;
    }
}