Laravel 8 migration on delete cascade not work

Hello i have 1 table parent and have 3 child table from table parent .

and i create migration like this

A.Parent

 public function up()
{
    Schema::create('kegiatan', function (Blueprint $table) {
        $table->id();
        $table->string('kode_rekening');
        $table->string('uraian');
        $table->string('anggaran');
        $table->string('anggaran_perubahan')->nullable();
        $table->timestamps();
        $table->softDeletes();
    });
}

B. Child no 1

 public function up()
{
    Schema::create('uraian', function (Blueprint $table) {
        $table->id();
        $table->unsignedBigInteger('kegiatan_id');
        $table->string('kode_rekening');
        $table->string('uraian');
        $table->string('anggaran');
        $table->string('anggaran_perubahan')->nullable();
        $table->timestamps();
        $table->softDeletes();

        $table->foreign('kegiatan_id')->references('id')->on('kegiatan')->onDelete('cascade');

    });
}

C. Child no 3

public function up()
{
    Schema::create('uraian_kegiatan', function (Blueprint $table) {
        $table->id();
        $table->unsignedBigInteger('uraian_id');
        $table->string('kode_rekening');
        $table->string('uraian');
        $table->string('anggaran');
        $table->string('anggaran_perubahan')->nullable();
        $table->timestamps();
        $table->softDeletes();

        $table->foreign('uraian_id')->references('id')->on('uraian')->onDelete('cascade');

    });
}

all is relate by foreign_key . i try to delete data on parent table like id 1 . but on my child , this data not deleted too . i think this is wrong because i set on delete casscade . i use Mysql and try to add 'InooDB' on my "config/Database" like this :

   'mysql' => [
        'driver' => 'mysql',
        'url' => env('DATABASE_URL'),
        'host' => env('DB_HOST', '127.0.0.1'),
        'port' => env('DB_PORT', '3306'),
        'database' => env('DB_DATABASE', 'forge'),
        'username' => env('DB_USERNAME', 'forge'),
        'password' => env('DB_PASSWORD', ''),
        'unix_socket' => env('DB_SOCKET', ''),
        'charset' => 'utf8mb4',
        'collation' => 'utf8mb4_unicode_ci',
        'prefix' => '',
        'prefix_indexes' => true,
        'strict' => true,
        'engine' => 'InnoDB',
        'options' => extension_loaded('pdo_mysql') ? array_filter([
            PDO::MYSQL_ATTR_SSL_CA => env('MYSQL_ATTR_SSL_CA'),
        ]) : [],
    ],

but its still didnt work , on first i see on this config/database ,this engine is set by 'null' ,

someone can help about this ? or give solution ? thanks you