Try adding a rectangular mask to say a graphic which is the size of a lower 3rd - nothing happens. Oh, forgot to say you have to "invert it 1st to see the base layer but then try to adjust the softness zilch happens to the shape as expected. Now the mask and softness features work great on a full screen layer so something is amiss. I did try the Oval mask too but still nothing.
Over to anyone else that would like to try it.
As an addition the graphic is layer 1 of 3
2 lower 3rd png graphic
3 jpeg photo already with it’s own mask.