Multiple entry points not working in Symfony 4.4

I have 2 user types on a website: Users and Vendors. Each of those types will use own login form. Therefore I've decided to create 2 separate firewalls in security.yaml:

security:
    encoders:
        App\Entity\Main\User:
            algorithm: bcrypt

        App\Entity\Main\Vendor:
            algorithm: bcrypt

    providers:
        users_provider:
            entity:
                class: App\Entity\Main\User
                property: email

        vendors_provider:
            entity:
                class: App\Entity\Main\Vendor
                property: email

    firewalls:
        dev:
            pattern: ^/(_(profiler|wdt)|css|images|js)/
            security: false

        main:
            pattern:   ^/
            anonymous: ~
            provider: users_provider
            form_login:
                check_path: security_login
                login_path: security_login
                csrf_token_generator: security.csrf.token_manager
                csrf_parameter: _csrf_token
                csrf_token_id: authenticate
                use_referer: true
                target_path_parameter: go_to

            logout:
                path: security_logout


        vendor:
            pattern: ^/vendor/
            anonymous: ~
            provider: vendors_provider
            form_login:
                check_path: security_vendor_login
                login_path: security_vendor_login
                csrf_token_generator: security.csrf.token_manager
                csrf_parameter: _csrf_token
                csrf_token_id: authenticate
                use_referer: true
                target_path_parameter: go_to
            logout:
                path: security_logout

    access_control:
        - { path: ^/%locales%/login, roles: ['IS_AUTHENTICATED_ANONYMOUSLY'] }
        - { path: ^/%locales%/vendor, roles: ['IS_AUTHENTICATED_ANONYMOUSLY'] }
        - { path: ^/%locales%, roles: ['IS_AUTHENTICATED_ANONYMOUSLY'] }

Login form for User user-login.html.twig:

{% extends 'main/base.html.twig' %}

{% block content %}
    <form action="{{ path('security_login') }}"
          method="POST">
        <input type="text"
               id="email-field"
               class="form-control"
               name="_username"
               value="{{ form._username.vars.value }}">

        <input type="password" id="password-field" class="form-control"
               name="_password">

        <input type="hidden" id="csrf" name="_csrf_token"
               value="{{ csrf_token('authenticate') }}">
    </form>
{% endblock %}

Login form for Vendor vendor-login.html.twig:

{% extends 'main/base.html.twig' %}

{% block content %}
    <form action="{{ path('security_vendor_login') }}"
          method="POST">
        <input type="text"
               id="email-field"
               class="form-control"
               name="_username"
               value="{{ form._username.vars.value }}">

        <input type="password" id="password-field" class="form-control"
               name="_password">

        <input type="hidden" id="csrf" name="_csrf_token"
               value="{{ csrf_token('authenticate') }}">
    </form>
{% endblock %}

Routes for login are defined in routes.yaml:

security_login:
    path: /login
    controller: App\Controller\Main\SecurityController:loginAction
    methods: [GET, POST]

security_vendor_login:
    path: /vendor/login
    controller: App\Controller\Main\SecurityController:vendorLoginAction
    methods: [GET, POST]

And the login methods in SecurityController:

public function userLoginAction(Request $request)
    {
        $error = $this->authenticationUtils->getLastAuthenticationError();
        $lastUsername = $this->authenticationUtils->getLastUsername();

        $form = $this->formFactory->create(LoginForm::class, [
            '_username' => $lastUsername
        ]);

        return new Response(
            $this->twigService->render(
                'main/security/user-login.html.twig',
                [
                    'form' => $form->createView(),
                    'error' => $error,
                ]
            ),
            200
        );
    }

    public function vendorLoginAction(Request $request)
    {
        $error = $this->authenticationUtils->getLastAuthenticationError();
        $lastUsername = $this->authenticationUtils->getLastUsername();

        $form = $this->formFactory->create(LoginForm::class, [
            '_username' => $lastUsername
        ]);

        return new Response(
            $this->twigService->render(
                'main/security/vendor-login.html.twig',
                [
                    'form' => $form->createView(),
                    'error' => $error,
                ]
            ),
            200
        );
    }

When I use the /login route then I'll be successfully logged in as User. However if I go to /vendor/login page and submit email and password the page just refreshes without any error messages and I'll not be authenticated. And in var/log/dev.log I see this

[2020-01-23 17:12:05] security.INFO: Populated the TokenStorage with an anonymous Token. [] 

Any ideas why this is happening?