Digital Light & Color

Running Precise Gaussion with the black slider of Amount at 100 and the white slider at 0, nothing happens. No part of the image is blurred. If the white slider is at 100 and the black at 0, the areas of the image corresponding to white areas of the mask are appropriately blurred. Is this the intended behavior?

No, it's not supposed to work that way. There appears to be some problem specific to this transformation caused by the Use Amount Mask as Blur Mask checkbox. Fixed for next release.