Laravel 中間テーブルはアルファベット順

顧客のテーブル（customers_table）とコースのテーブル（courses_table）を多対多のリレーションで作るときに
”base table or view not found 1146 table”と怒られたはなし。

環境

laravel 5.5
laravel-admin 1.8.11

顧客テーブル

php artisan make:migration create_customers_table --create=customers

customers_table

use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreateCustomersTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('customers', function (Blueprint $table) {
            $table->bigIncrements('id');
            $table->string('customer_firstname', 100);
            $table->string('customer_lastname', 100);
            $table->timestamps();
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('customers');
    }
}

コーステーブル

php artisan make:migration create_courses_table --create=courses

courses_table

<?php

use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreateCoursesTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('courses', function (Blueprint $table) {
            $table->bigIncrements('id');
            $table->string('course_name', 100);
            $table->timestamps();
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('courses');
    }
}

顧客とコースの中間テーブル

×ダメなケースのテーブル customer_course

php artisan make:migration create_customer_course_table --create=customer_course

○良いケースのテーブル course_customer

php artisan make:migration create_course_customer_table --create=course_customer

<?php

use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreateCourseCustomerTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('course_customer', function (Blueprint $table) {
          $table->unsignedBigInteger('customer_id');
          $table->unsignedBigInteger('course_id');
          $table->primary(['customer_id', 'course_id']);
          //外部キー制約
          $table->foreign('customer_id')->references('id')->on('customers')->onDelete('cascade');
          $table->foreign('course_id')->references('id')->on('courses')->onDelete('cascade');
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('course_customer');
    }
}

ModelとController

App/Models/Customer

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class Customer extends Model
{
  public function courses() {
    return $this->belongsToMany('App\Models\Course');
  }
}

App/Models/Course

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class Course extends Model
{
 customers() {
    return $this->belongsToMany('App\Models\Customer');
  }
}

App/Admin/CustomerController.php

<?php

namespace App\Admin\Controllers;

use App\Models\Customer;
use App\Models\Course;
use Encore\Admin\Controllers\AdminController;
use Encore\Admin\Form;
use Encore\Admin\Grid;
use Encore\Admin\Show;

class CustomerController extends AdminController
{
中略

    protected function form()
    {
        $form = new Form(new Customer());
        $form->text('customer_lastname', __('苗字'))->required(true);
        $form->text('customer_firstname', __('名前'))->required(true);
        //コース
        $form->multipleSelect('Courses','コース')->options(Course::all()->pluck('course_name','id'));
        return $form;
    }

}