I've noticed that too sometimes. I also notice that sometimes after I've scaled the hair, and then repose the figure that the hair vanishes off the top of the head. it's still listed in the drop down, but no where to be found in the pose window. It's not all of the time, just sometimes. I too would like to know a work around/solution for these.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi