As the title, the 'laravel_session' cookie is not set on the production server, and the form is failed to process.
I'm running Laravel version 5.6, PHP 7.2.4-1 and ubuntu16.04.1 on the production server.
However, I run the same code and setting locally in MAMP. it's working fine. The 'laravel_session' cookie is created automatically, and I can view it inside the browser.