Problem resolved.

TBH, after pouring over configuration properties on two machines and some minor code refactoring (and I mean really minor) the "Can't find std.ixx" problem is gone. I can't put my finger on what exactly I did that solved it but could easily have been inconsistent configuration settings across the 3 modules and 7 other compilation units combined with MS's confusing array of module implementation guidance.

I'm glad this is over. Sorry, that doesn't help the community much :-( Back to productive work.