It's that was because you're looking at an ideal surface.
Inside a bulk medium such as a conductor, the electric field is in the same direction as the current. On the surface (i.e., at the interface between two media), the electric field in the second medium will typically be normal to the surface if the second medium is an insulator and the first medium is a conductor.
HFSS by default does not solve inside bulk metals; it treats only the surface as boundary conditions. If you want to see the fields inside, select "Solve Inside".