Duct overrides behave differently in two drawings

[Anonymous]

I have two drawings which behave differently to System Styles in the
following way:

1. System Definition has no layer key defined on the Design Rules tab. It
does have an Override Value in the Major field. When add a duct in this
drawing, the duct is drawn on the layer with the proper override as part of
the duct's layer.
2. System Definition has the same settings as drawing 1. In this drawing
the duct is drawn on STND major field. If I create a Layer Key on this
drawing which has the Major field set to the desired Major field, it appears
properly within the drawing.

I have tried turning Overrides on/off. No Effect.
Renaming style in 2 and copying the style from 1. No Effect.
Have looked at Options but don't see anything which would make a difference.

Is there some toggle which I am overlooking.