Websocket not responding on Heroku in production mode

[porta8080]

Everything works fine in development in localhost, Rails version is 4.2.6. But only connection is established when I'm working in production mode on Heroku. Rails version is 4.2.1.

I receive this on console after dispatcher.on_open

Connection has been established: Object {connection_id: "239cfd5f-6e2d-48f3-a5e1-cdc2f686bfb3"}

After that I keep sending data, but receiving nothing back

...
["get_sessions",null,{"id":110523}] 35
10:08:59.066
["get_sessions",null,{"id":99775}] 34
10:09:09.067
["get_sessions",null,{"id":99688}] 34
10:09:20.066
["get_sessions",null,{"id":99662}] 34
10:09:31.066
["get_sessions",null,{"id":97249}] 34
10:09:42.066
["get_sessions",null,{"id":116865}] 35
10:09:52.067
["get_sessions",null,{"id":94010}]

My configuration file is as default.

Any insights on what it could be?