The only mirror shaders in common.shader are mirror1, mirror2, and qer_mirror. None of them work. (Also, for cameras, portal, qer_portal and timportal do not work).
My files are up-to-date. shaderlist.txt references common.shader which contains mirror1|2
I've tried EVERYTHING. All the accepted methods (Bubba's Arena Tutorials, the entity description/info for misc_portal_surface, the radiant manual) have failed for me, and i'm following them EXACTLY. It Just Doesn't Work!!