The same problem has been driving me nuts too.I found that if the class names in cfg models has been changed it stuffs up the faces.I solved this by entering the original p3d name above my first class name.eg:
class CfgModels
{
class Default
{
sections[] = {};
sectionsInherit="";
};
class Head : Default
{
sections[] = {"osobnost"};
};
class Man:Default {};
class DX_rus_sldr:Man {};
class wrusnagant:Man {};
class wrusnagants:Man {};
class wrussvt:Man {};
DX_rus_sldr, being the original name,This solved my problem anyway.Hope it helps you.