Hi Alex,
They are there, you might just not be able to see them; the size of those dots are scaled, with the Brush Radius and also, if they are too far from the Plane (Sculptable Object), they will disappear.
So, if you move your Brush around, you’ll probably notice (some of) them. You can also increase the Brush Radius and they will become more apparent. Or just zoom out, then the Brush will become relatively larger, compared to the Plane.