Why can’t I take pictures in autonomous flight using SPIRAL?

My doubt is quite simple, when i’m planning a path to do an autonomous mission I can’t take pictures when I select the box SPIRAL, when I deselect this options the pictures counter raise, if I select SPIRAL it returns to zero.

In my opinion, mission using spiral can be a time saver compared to the usual path, becouse the copter will not fully stops when makes a turn, spiral will only reduce a little the speed and make a turn.

it was designed for lawnmower, ill add the ability to take images as well