I have been working with the blur gallery using path and spin blur. After adding the blur, I open a mask to adjust the amount of the effect in specific areas. With a black brush, the mask will remove the effect, but with a white brush, it will not put the effect back, as it should with a mask. Has anyone else noticed this? Radial blur does the same thing.
Could you please post screenshots with the pertinent Panels visible?
It sounds like you have your brush in darken or multiple blend mode.
You nailed it. I was in multiply blend mode. I changed it to normal and the mask works normally. Problem solved, thank you.