The selection offered by ‘Subject Mask’ is usually very good, but in many cases it isn’t perfect. It’s often necessary to correct this subject selection.
If you combine this ‘corrected’ subject mask with, for example, a radial filter, the correction is not taken into consideration. Only the mask automatically found by the AI is taken into account. It would be nice if you could correct this subject selection and have the corrected mask recognised as the subject.