PFPX flight plans/routes should be saved in the default P3Dv4 .PLN format, in Documents\Prepared v4 Files, and not in X:\Prepar3D v4\Captain_Sim\navigation\routes, as it does not save in the newer Captain Sim .RT format. It only saves in the older .RT format compatible with the oder CS 757 v4.6, and CS 767 v1.5.