Arrows for stacked bars unmovable from lower half to upper half and vice versa.

idk if this is a bug or a forced feature, but whenever i have a few labels like this and i would like to sort them, i cannot make the upper half go to the lower half and vice versa. E.g. "12+" cannot be forced to the bottom by pressing the arrow down (though it can move up and down in the other positions in the top half). Why is this? Am i just creating this mistake myself somehow? Image Image likewise, "5-7" cannot be moved upwards from its position