Why do you even need a 3D View template? You can apply a plan view template to a 3d view and it works just fine. Whatever the issue is, it’s just best to avoid these half-baked templates because they have no purpose.
Ps. I would consider what you are trying to accomplish. You are applying the view template to a 3D View. The idea here is that you apply that view template, and then export that view to Navisworks. It sounds honky dory in theory, but I have a feeling that for a View template to actually take effect it needs to regenerate the model. Try putting a doc.Regenerate() between view template being applied and the actual view getting exported.