Photoshop CC 2015.5.1 - When adding noise to the blurred area it is not seamless. This happens with all filters in the blur gallery except with the spin blur filter where the noise is smoothly blended to the edge of the blurred area. These sample images have such a high amount of blur just to show the problem I have with the filters. It occurs on both Mac and Windows versions of Photoshop.
That's because you have a very high level of noise coming up to an area with little or no original noise. The feature is not intended to be used this way. To attempt to taper the noise any further would result in a noticeable band of smoothness on images where you are adding noise at a level that closely matches the original noise.