Chart: Hovering over datapoint where series is undefined, adds an inactive state to the series for the whole chart

[jsjsat]

Bug Report

Highcharts 7 introduced a new default to the inactive state of a series, which you can see when you hover over a timestamp where there is no value for a series. What happens is, that the series gets an opacity of 0.2 for the rest of the chart, which is very confusion especially for stacked area charts.

Possible Solution

As @ffriedl89 suggested opacity in the inactive value of the series plotoptions should be set to 1.

I will create a pr shortly!