For the windshield and side windows of the Vehicles to show with path tracer, make sure the translucent components parts have “Visible in Ray Tracing” enabled when you select them in the BP and that the static mesh themselves have the Support Raytracing option enabled. It was off for some reason and that’s what did it for me. I also swapped the shader for something simpler for debugging on the veh_windshield and veh_windows.
Hope this helps.