After installing hte latest highcharts DLL MinorGridLineDashStyle is accepting on Hashtable but when coming into script it is giving error

public Hashtable MinorGridLineDashStyle { get; set; }

And from UI when tried manually modifiying and putting the below block it is working

"minorGridLineDashStyle" : "Dot"

Now the issue is we cannot handle it from C#. Is there any workaround for this issue or am i doing something wrong.

Expecting to load line chart

    at I.dashstyleSetter (https://code.highcharts.com/highcharts.js:8:37363)
    at I.<anonymous> (https://code.highcharts.com/highcharts.js:8:35183)
    at C (https://code.highcharts.com/highcharts.js:8:1553)
    at I.attr (https://code.highcharts.com/highcharts.js:8:34975)
    at Object.renderGridLine (https://code.highcharts.com/highcharts.js:8:76562)
    at Object.render (https://code.highcharts.com/highcharts.js:8:76026)
    at N.renderMinorTick (https://code.highcharts.com/highcharts.js:8:101747)
    at https://code.highcharts.com/highcharts.js:8:102632
    at Array.forEach (<anonymous>)
    at N.render (https://code.highcharts.com/highcharts.js:8:102610)", undefined