Symfony 4 make:entity --regenerate fail with: No entities were found in the "App" namespace

from composer.json

{
    "name": "symfony/website-skeleton",
    "type": "project",
    "license": "MIT",
    "description": "A skeleton to start a new Symfony website",
    "require": {
        "php": "^7.1.3",
        "ext-iconv": "*",
        "sensio/framework-extra-bundle": "^5.1",
        "symfony/apache-pack": "^1.0",
        "symfony/asset": "^4.0",
        "symfony/console": "^4.0",
        "symfony/expression-language": "^4.0",
        "symfony/flex": "^1.0",
        "symfony/form": "^4.0",
        "symfony/framework-bundle": "^4.0",
        "symfony/lts": "^4@dev",
        "symfony/monolog-bundle": "^3.1",
        "symfony/orm-pack": "^1.0",
        "symfony/process": "^4.0",
        "symfony/security-bundle": "^4.0",
        "symfony/serializer-pack": "*",
        "symfony/swiftmailer-bundle": "^3.1",
        "symfony/translation": "^4.0",
        "symfony/twig-bundle": "^4.0",
        "symfony/validator": "^4.0",
        "symfony/web-link": "^4.0",
        "symfony/webpack-encore-pack": "*",
        "symfony/yaml": "^4.0"
    },
    "require-dev": {
        "symfony/browser-kit": "^4.0",
        "symfony/css-selector": "^4.0",
        "symfony/debug-pack": "*",
        "symfony/dotenv": "^4.0",
        "symfony/maker-bundle": "^1.5",
        "symfony/phpunit-bridge": "^4.0",
        "symfony/profiler-pack": "*",
        "symfony/web-server-bundle": "^4.0"
    },
    "config": {
        "preferred-install": {
            "*": "dist"
        },
        "sort-packages": true
    },
    "autoload": {
        "psr-4": {
            "App\\": "src/"
        }
    },
    "autoload-dev": {
        "psr-4": {
            "App\\Tests\\": "tests/"
        }
    },
    "replace": {
        "symfony/polyfill-iconv": "*",
        "symfony/polyfill-php71": "*",
        "symfony/polyfill-php70": "*",
        "symfony/polyfill-php56": "*"
    },
    "scripts": {
        "auto-scripts": {
            "cache:clear": "symfony-cmd",
            "assets:install --symlink --relative %PUBLIC_DIR%": "symfony-cmd"
        },
        "post-install-cmd": [
            "@auto-scripts"
        ],
        "post-update-cmd": [
            "@auto-scripts"
        ]
    },
    "conflict": {
        "symfony/symfony": "*"
    },
    "extra": {
        "symfony": {
            "allow-contrib": false
        }
    }
}

from doctrine.yaml:

# /config/packages/doctrine.yaml
doctrine:
    dbal:
        default_connection: training
        connections:
            training:
                dbname:   "training"
                driver:   "pdo_mysql"
                host:     "localhost"
                port:     "3306"
                user:     "userdb"
                password: "XXXXXXXXXX"
                charset:  UTF8
                mapping_types:
                    bit: boolean
    orm:
        auto_generate_proxy_classes: "%kernel.debug%"
        default_entity_manager: training
        entity_managers:
            training:
                connection: training
                auto_mapping: true

the command:

php bin/console doctrine:mapping:import --em=training App\Entity annotation --path=src/Entity

produce into src/Entity the Course.php entity:

<?php

namespace App\Entity;

use Doctrine\ORM\Mapping as ORM;

/**
 * Course
 *
 * @ORM\Table(name="course", indexes={@ORM\Index(name="id_product_idx_1", columns={"id_product"}), @ORM\Index(name="enabled_idx_1", columns={"enabled"}), @ORM\Index(name="sort_idx_1", columns={"sort"})})
 * @ORM\Entity
 */
class Course
{
    ....

after run into the console:

php bin/console make:entity --regenerate App

this fail with error:

No entities were found in the "App" namespace

same for

php bin/console make:entity --regenerate App\Entity 

if i try

php bin/console make:entity --regenerate App\Entity\Course

the output is

Could not find Doctrine metadata for "App\Entity\Course". Is it mapped as an entity?

what i'm doing wrong?