Situation:
In a field, I want to have 0.4% minimum slope and a max slope change % of 0.1%.  By doing this I clearly see two zones that are real deep in the field and OSDv1.3 is telling to fill these holes up to 76cm.  To avoid this I created 2 new design zones and changed the properties to 0.4% min slope and no max slope change %.  But since the Boundary zone property is set up at 0.1% max slope change, my 2 design zones remains at 0.1% even though I didn't even check the box for max slope change%.

To make it work, I had to do the opposite.  Keep my boundary zone property at 0.4% min slope and no max slope change % and then create a big design zone which doesn't include the 2 zones I want to keep at no max slope change %.

Solution:
The way the subzones work is that you need to enter a value into the subzone to override the setting in the boundary, otherwise it will default to the boundary setting.  So just set the subzones maximum slopes to something like 3% and try again.