hey guys, i am using app router 13.4 and the not-found.tsx custom page worked for me suddenly its stopped to work and i always get the default 404 page someone knows how to fix that?
the not-found.tsx file is in my root app folder
not found page code :

import type { Metadata, NextPage } from 'next';
import Image from 'next/image';
import Link from 'next/link';

export const metadata: Metadata = {
title: '404',
};

const NotFound: NextPage = () => {
return (
<section className='error-404-main-container'>
<div>404</div>
</section>
);
};

export default NotFound;

that how i am importing:

import { notFound } from 'next/navigation';
const article: ArticleModel | null = await articleService.getArticle(articleId);

if (!article) {
return notFound();
}