Since HaxeFlixel piggybacks off of OpenFL, there should be a project file somewhere, like in the images shown in this documentation:
And mentioned here:
Now, I don’t use Haxeflixel, so I can’t be 100% certain, but my guess is you’ll have to add the FLX_DRAW_QUADS flag in your project.xml file somewhere like so:
<define name="FLX_DRAW_QUADS" />