Mongoose Schema created using CommonJS not working again after porting to Module

Prerequisites

• I have written a descriptive issue title

Mongoose version

6.7.1

Node.js version

14.19.1

MongoDB version

4.11.0

Operating system

macOS

Operating system version (i.e. 20.04, 11.3, 10)

MacOS Monterey, 12.4

Issue

I started out my Mongoose Schema declarations using CommonJS as shown below and populate was working perfectly.

For CommonJS I have:

author.js

const mongoose = require('mongoose');

const AuthorSchema = new mongoose.Schema({
    _id: mongoose.Schema.Types.ObjectId,
    first_name: String,
    last_name: String,
    email: String,
}, {
    timestamps: {
        createdAt: 'created_at',
        updatedAt: 'updated_at'
    }
});

module.exports = mongoose.model('Author', AuthorSchema);

comment.js

const mongoose = require('mongoose');

const CommentSchema = new mongoose.Schema({
    _id: mongoose.Schema.Types.ObjectId,
    text: String,
    author: {
        type: mongoose.Schema.Types.ObjectId,
        ref: 'Author'
    }
}, {
    timestamps: {
        createdAt: 'created_at',
        updatedAt: 'updated_at'
    }
});

module.exports = mongoose.model('Comment', CommentSchema);

and the below query worked flawlessly when using CommonJS

let comments = await Comment.find({ author: authorId })
        .populate("author", 'first_name last_name _id').limit(10);

Now, my team wanted us to move away from CommonJS to modules and so I added type:module to my package.json file and attempted to refactor the schema declarations above to the following:

new_author.js

import mongoose from 'mongoose';

const AuthorSchema = new mongoose.Schema({
    _id: mongoose.Schema.Types.ObjectId,
    first_name: String,
    last_name: String,
    email: String,
}, {
    timestamps: {
        createdAt: 'created_at',
        updatedAt: 'updated_at'
    }
});

export default mongoose.model('Author', AuthorSchema);

and

new_comment.js

import mongoose from 'mongoose';

const CommentSchema = new mongoose.Schema({
    _id: mongoose.Schema.Types.ObjectId,
    text: String,
    author: {
        type: mongoose.Schema.Types.ObjectId,
        ref: 'Author'
    }
}, {
    timestamps: {
        createdAt: 'created_at',
        updatedAt: 'updated_at'
    }
});

export default mongoose.model('Comment', CommentSchema);

and all of a sudden the following query no longer works

let comments = await Comment.find({ author: authorId })
            .populate("author", 'first_name last_name _id').limit(10);

The error I keep getting back is

MissingSchemaError: Schema hasn't been registered for model "Author".

This is unbelievable. As you can see above, nothing changed other than using imports and export default statements.

[hashweather]

I changed ref to authors and issue still persists

[hashweather]

This is really weird. The authors collection already has over 1k documents in it so how is it possible that its schema has not been created?

Please note that this issue doesn’t happen if both services move back to CommonJS. It seems to only happen when we switched to module