When I use the radial filter, I select the radial filter icon, adjust eg exposure, then I hightlight the part of the photo I wish to alter. The problem is that when for example, I inverse mask the selection (to only alter eg a persons face), this area goes blurry. I can alter the exposure but it remains blurred unless I delete the radial filter on eg the face.
Have you checked the other sliders? Maybe sharpness or clarity are all the way to the left.