(ometimes I just can not stop myself and just had to look at AgingTV.) I
think I found the problem. If everything is unchecked and then one of the
3 items of Scratch, Pits, or Dust is checked BUT set to zero, you can still
see that item in the compositor. Grain is either on or off and works as
expected.
The good news is that at least you can designate which type of aging you
want, be it grain, scratch, pits, dust, or all or none. I will log a BT on
this in case anyone wants to look at it in the future.