Highcharts heatmap color does not match legend - highcharts

Question

I'm new to highcharts, but I seem to have an issue with the display of the large heatmap. The colors in the legend don't seem to match the colors in the actual chart.
The following is my chart configuration code.
function load_team_effort_by_day_of_week_heat_map(ele, config)
{
var self = $(ele);
var days = ["Monday", "Tuesday", "Wednesday", "Thursday","Friday", "Saturday", "Sunday"]
load_data(self, function(response)
{
var div = $("<pre/>")
.attr("id","csv")
.css("display","none");
div.html(response.data);
$("body").append(div);
var chart_container = self.attr("chart-container");
$("#"+chart_container).css("width","100%");
var min = new Date(response.min)
var max = new Date(response.max)
var max_value = response.max_range
var mid_range = parseFloat(max_value/4);
Highcharts.chart(chart_container, {
data: {
csv: document.getElementById('csv').innerHTML
},
chart: {
type: 'heatmap',
margin: [60, 10, 80, 50]
},
boost: {
useGPUTranslations: true
},
title: {
text: '',
align: 'left',
x: 40
},
subtitle: {
text: '',
align: 'left',
x: 40
},
xAxis: {
title: {
text: config.xlabel
},
type: 'datetime',
min: Date.UTC(min.getFullYear(), min.getMonth(), min.getDate()),
max: Date.UTC(max.getFullYear(), max.getMonth(), max.getDate()),
labels: {
align: 'left',
x: 5,
y: 14,
format: '{value:%b-%d-%Y}' // long month
},
showLastLabel: false,
tickLength: 16
},
yAxis: {
title: {
text: config.ylabel
},
labels: {
format: '{value}'
},
minPadding: 0,
maxPadding: 0,
startOnTick: false,
endOnTick: false,
tickPositions: [0, 1, 2, 3, 4, 5, 6],
tickWidth: 1,
min: 0,
max: 6,
reversed: true
},
colorAxis: {
stops: [
[0, '#EEEEEE'],
[mid_range, '#00ee33'],
[max_value, '#00ee33']
],
min: 0,
max: max_value,
startOnTick: false,
endOnTick: false,
labels: {
format: '{value}'
}
},
tooltip: {
formatter: function () {
var d = new Date(this.point.x)
var todate=d.getDate();
var tomonth=d.getMonth()+1;
var toyear=d.getFullYear();
var original_date=tomonth+'/'+todate+'/'+toyear;
return '<b>' + original_date + ', <b>' +
this.point.value + '</b> on <br><b>' + days[this.point.y] + '</b>';
}
},
series: [{
boostThreshold: 100,
borderWidth: 0,
nullColor: '#EEEEEE',
colsize: 7 * 24 * 36e5, // one week
turboThreshold: Number.MAX_VALUE // #3404, remove after 4.0.5 release
}]
});
self.parents('.white-background').removeClass("loadingdv");
self.parents('.white-background').find(".lodimg").remove();
//Remving extra div for legends on rite side
self.parents('.white-background').find(".legendcontainer").remove();
});
}