How do I format datetime argument labels? - devexpress

Question

I'm trying to make a chart with the datetime argument labels formatted as MMM yyyy, e.g. Mar 2017. However, when I try to format in the same way as the documentation (even trying the example given - MM/d), the argument axis labels disappear.
Here is what I've noticed, from trying various formats (examples are all based on 10 March 2017):
Removing format works fine, but labels show the default format
MMM yyyy - labels disappear
M - month labels show correctly (e.g. 3)
MM - labels all show '00'
MMM - labels disappear
MMMM - labels disappear
y - labels show correct year (e.g. 2017)
yy - labels show correctly (e.g. 17)
yyyy - labels disappear
MMMM y - labels show (e.g. March 2017)
M y - labels disappear
MM y - labels disappear
MMM y - labels disappear
MMMM-y - labels disappear
My code:
HTML:
<div id="spline-chart"></div>
JavaScript:
$(function($) {
$("#spline-chart").dxChart({
series: [{
argumentField: "Date",
type: "spline",
valueField: "Spend",
name: "Spend"
}],
tooltip: {
enabled: true
},
dataSource: {
store: new DevExpress.data.ArrayStore({
data: [
{ Date: "2016-11-25", Spend: 142 },
{ Date: "2016-12-02", Spend: 562 },
{ Date: "2016-12-09", Spend: 425 },
{ Date: "2016-12-16", Spend: 449 },
{ Date: "2016-12-23", Spend: 239 },
{ Date: "2016-12-30", Spend: 121 },
{ Date: "2017-01-06", Spend: 322 },
{ Date: "2017-01-13", Spend: 427 },
{ Date: "2017-01-20", Spend: 196 },
{ Date: "2017-01-27", Spend: 201 },
{ Date: "2017-02-03", Spend: 256 },
{ Date: "2017-02-10", Spend: 399 },
{ Date: "2017-02-17", Spend: 403 },
{ Date: "2017-02-24", Spend: 432 },
{ Date: "2017-03-03", Spend: 239 },
{ Date: "2017-03-10", Spend: 127 },
{ Date: "2017-03-17", Spend: 508 },
{ Date: "2017-03-24", Spend: 514 },
{ Date: "2017-03-31", Spend: 338 },
{ Date: "2017-04-07", Spend: 184 }
]
})
},
argumentAxis: {
grid: { "visible": true },
minorGrid: { "visible": true },
argumentType: "datetime",
tickInterval: { months: 1 },
label: {
format: "MMM yyyy"
}
}
});
});
Here's the codepen link.
How can I format the axis to 'Mar 2017'?