Canvas loses alpha when drawing on bitmapData

[Sheepolution]

I originally asked this question on the OpenFL forums, but it might just be the case that this is more of an Haxeflixel problem.

In HaxeFlixel I have a camera, and I want to draw the canvas of the camera to a sprite. So I do:
someSprite.pixels.draw(myCamera.canvas)
canvas is of the type Sprite. But when drawing the canvas to the bitmapData (pixels) the alpha gets lost. I can’t solve this with a colorTransform, because it’s the alpha of the individual sprites that get drawn onto the canvas, with each their own alpha.
Now it might be the case that the alpha is already lost in the canvas, and not necessarily when the canvas gets drawn onto the bitmapData, but I’m not sure how I can be sure about that.
So perhaps instead of a canvas I can make a bitmapData where I draw my sprites on. But if someone has a solution for the canvas problem that would be great!