Hyperloop named route as undefined #2

potential bug with hyper-model. In a fresh rails 5.1 install. When you first access the Model you get a failed POST to http://localhost:5000/undefined/execute_remote. Changing mount Hyperloop::Engine => '/undefined’ in route.rb gets it working so I am assuming the client is not getting a variable set somewhere. I have looked at the code trying to figure out where this is happening but its not clear to me. Is there a config setting not being set?