Trouble getting D3-generated SVG to appear on screen consistently - d3.js

Question

I'm currently working on a Javascript project where I am trying to render the following chart using d3.
The problem, though is that sometimes svg elements for the yellow chart fails to show sometimes (and at random). The problem usually goes away after I refresh the page (once or multiple times). When this happens, the browser dev tools still show that the svg elements are present:
This only happens to the yellow chart and never to the blue chart.
This is the function that I used to create the chart:
function makeGraphs(filterDisease,filterAir) {
var width = 840;
var height = 110;
var barPadding = 1;
var dateFormat = d3.time.format("%Y-%m-%d");
var xScale = d3.time.scale()
.range([0,width-50]);
var yScaleDisease = d3.scale.linear()
.range([height,0]);
var yScaleAir = d3.scale.linear()
.range([0,height]);
var xAxis = d3.svg.axis()
.scale(xScale)
.orient("top");
var yAxisDisease = d3.svg.axis()
.scale(yScaleDisease)
.orient("left")
.ticks(5);
var yAxisAir = d3.svg.axis()
.scale(yScaleAir)
.orient("left")
.ticks(5);
var svgDisease = d3.select("body").select("#comparison-chart")
.append("svg")
.attr("class","chart-comparison")
.attr("id","chart-comparison-disease")
.attr("width",width)
.attr("height",height);
var svgAir = d3.select("body").select("#comparison-chart")
.append("svg")
.attr("class", "chart-comparison")
.attr("id", "chart-comparison-air")
.attr("width", width)
.attr("height", height + 20);
d3.json("/datasets/disease", function(error, datasetDisease) {
datasetDisease.forEach(function(d) {
d["date"] = dateFormat.parse(d["date"]);
d["total"] = 0
for (i=0;i<filterDisease.length;i++) {
d["total"] += d[filterDisease[i]];
}
});
var ndxDisease = crossfilter(datasetDisease);
var dateDimDisease = ndxDisease.dimension(function(d) {return d["date"];});
var total_disease = dateDimDisease.group().reduceSum(function(d) {return d["total"];});
var datasetDisease_formatted = total_disease.all();
xScale.domain([new Date(datasetDisease_formatted[0]["key"]), new Date(datasetDisease_formatted[datasetDisease_formatted.length -1]["key"])]);
yScaleDisease.domain([0,d3.max(datasetDisease_formatted,function(d) {return d["value"];})]);
svgDisease.selectAll("rect")
.data(datasetDisease_formatted)
.enter()
.append("rect")
.attr("x", function(d) { return xScale(new Date(d["key"]));})
.attr("y", function(d) { return yScaleDisease(d["value"]); })
.attr("width", (width-50)/datasetDisease_formatted.length - barPadding)
.attr("height", function(d) {
return height - yScaleDisease(d["value"]);
})
.attr("fill", "#19C3CD")
.attr("transform", "translate(50,0)");
svgDisease.append("g")
.attr("class", "y axis")
.attr("transform", "translate(30,0)")
.call(yAxisDisease);
svgDisease.append("text")
.text("Disease Records")
.attr("x", 650)
.attr("y", 20);
});
d3.json("/datasets/air", function(error, datasetAir) {
datasetAir.forEach(function(d) {
d["date"] = dateFormat.parse(d["date"]);
d["total"] = 0
for (i=0;i<filterAir.length;i++) {
d["total"] += d[filterAir[i]];
}
});
var ndxAir = crossfilter(datasetAir);
var dateDimAir = ndxAir.dimension(function(d) {return d["date"];});
var total_pollutants = dateDimAir.group().reduceSum(function(d) {return d["total"];});
var datasetAir_formatted = total_pollutants.all();
yScaleAir.domain([0, d3.max(datasetAir_formatted, function(d) {return d["value"];})])
svgAir.selectAll("rect")
.data(datasetAir_formatted)
.enter()
.append("rect")
.attr("x", function(d) { return xScale(new Date(d["key"]));})
.attr("y",0)
.attr("width", (width-50)/datasetAir_formatted.length - barPadding)
.attr("height", function(d) {
return yScaleAir(d["value"]);
})
.attr("fill", "#FED40A")
.attr("transform", "translate(50,0)");
svgAir.append("g")
.attr("class","x axis")
.attr("transform", "translate(50," + (height+20) + ")")
.call(xAxis);
svgAir.append("g")
.attr("class", "y axis")
.attr("transform", "translate(30,0)")
.call(yAxisAir);
svgAir.append("text")
.text("Air Pollutant")
.attr("x", 650)
.attr("y", 90);
});
};
Is there any problem with my code that is causing this issue? Oh, and I'm using crossfilter as well to format my JSON data.