Use the function fn_get_runtime_company_id() (or in template code {""|fn_get_runtime_company_id}. Using $runtime.company_id only works for multiple storefronts or for MVE. It is a hack they did way back in early version 4 for compatibility where they should have just converted the single-store company to company_id 1. But now we live with it. You can look at the fn_get_runtime_company_id() function to see how it uses $runtime.company_id to determine the actual real company_id.