Some fabrications that my company makes, require some faces to be masked while the rest of the product is powder coated.  So while I can apply a general appearance to most parts I have to treat the masked component at its part document level, by creating a face with a split line, say.

Normally this transfers upwards through parent assemblies correctly, but if in one assembly you create an Assembly Feature involving the masked part, the assemblies further up do not show the masked face (initially maybe but not after a rebuild).  It's as if the assembly feature cancels the part document face appearance and applies an overall appearance.

Perhaps the simplified block images may explain.  Part1 has a face of different appearance to the rest of the part, the face made by a Split Line. The masked part Part1, shows in Assem1 OK.  Then an extruded cut is applied to the Part in Assem1.  Parent assembly Assem2 however does not show the masked area.

Does anyone know why this happens, and to prevent it?

Thanks, Janek, SW2014