When multiple locales are used, it only works with the default one

[vvasiloi]

The Sylius\Bundle\LocaleBundle\Context\RequestBasedLocaleContext gets the locale from the _locale request attribute, which is set after the route is matched, since it's a path parameter, therefore it's no available during the route matching.
Because this context does not return a locale, the next context Sylius\Component\Locale\Cont ext\ProviderBasedLocaleContext will return the default one.

Temporary solution:

namespace App\Context;

use Sylius\Component\Locale\Context\LocaleContextInterface;
use Sylius\Component\Locale\Context\LocaleNotFoundException;
use Sylius\Component\Locale\Provider\LocaleProviderInterface;
use Symfony\Component\HttpFoundation\RequestStack;

final class UrlBasedLocaleContext implements LocaleContextInterface
{
    /**
     * @var RequestStack
     */
    private $requestStack;

    /**
     * @var LocaleProviderInterface
     */
    private $localeProvider;

    /**
     * @param RequestStack $requestStack
     * @param LocaleProviderInterface $localeProvider
     */
    public function __construct(RequestStack $requestStack, LocaleProviderInterface $localeProvider)
    {
        $this->requestStack = $requestStack;
        $this->localeProvider = $localeProvider;
    }

    /**
     * @throws LocaleNotFoundException
     */
    public function getLocaleCode(): string
    {
        $request = $this->requestStack->getMasterRequest();

        if (null === $request) {
            throw new LocaleNotFoundException('No master request available.');
        }

        $pathInfo = $request->getPathInfo();
        $availableLocalesCodes = $this->localeProvider->getAvailableLocalesCodes();

        foreach ($availableLocalesCodes as $localeCode) {
            if (false !== strpos($pathInfo, sprintf('/%s/', $localeCode))) {
                return $localeCode;
            }
        }

        throw new LocaleNotFoundException('No available locale found in the url.');
    }
}

services:
    App\Context\UrlBasedLocaleContext:
        tags:
            - { name: sylius.context.locale, priority: -64 }