Color dynamics pen pressure not working

[#1]

I'm trying to fade from foreground to background using color dynamics setting.

When I initially press on the canvas, depending on how hard I pressed, the color is determined.  However, mid stroke, the pressure doesn't change the color or fade from one color to the other... its just a constant value determined by how hard I initially pressed. 

How do I get it to fade mid-stroke like I expected and have read it should?  I thought that was the normal behavior.  I have no other options enabled, it is a basic soft round brush with 10% smoothing and no other pressure controls.

[#2]

I'm trying to fade from foreground to background using color dynamics setting.

When I initially press on the canvas, depending on how hard I pressed, the color is determined.  However, mid stroke, the pressure doesn't change the color or fade from one color to the other... its just a constant value determined by how hard I initially pressed. 

How do I get it to fade mid-stroke like I expected and have read it should?  I thought that was the normal behavior.  I have no other options enabled, it is a basic soft round brush with 10% smoothing and no other pressure controls.

[#3]

[#4]

Hi, go to the contextual menu and clear the brush

LMK if that works