It looks like something may be happening with:
grid.load(url, 'jsarray')
I am testing v412 and noticed that loading a grid from a jsarray is failing.
So checking the dhtmx docs it’s happening here too:
http://dhtmlx.com/docs/products/dhtmlxGrid/samples/12_initialization_loading/08_init_grid_jsarray.html
When the page is first loaded, after grid.init() it’s calling:
mygrid.load("../common/_data.js","jsarray");
And the grid is empty.