nestjs - NestJS ConfigService returns undefined values during async TypeORM configuration on app startup

Question

I'm trying to setup configuration for my NestJS app by following some of the following documentation:

Config: https://docs.nestjs.com/techniques/configuration

TypeORM: https://docs.nestjs.com/techniques/database#async-configuration

I've added a .env file to the root of my project (same level as package.json) with the following values:

DB_URL=localhost
DB_USER=root
DB_PASSWORD=root
DB_NAME=test_db

In my app.module.ts, I import the following modules:

import { Module } from '@nestjs/common';
import { TypeOrmModule } from '@nestjs/typeorm';
import { ConfigModule, ConfigService } from '@nestjs/config';

import { AppController } from './app.controller';
import { AppService } from './app.service';

@Module({
  imports: [
    ConfigModule.forRoot(),
    TypeOrmModule.forRootAsync({
      imports: [ConfigModule],
      useFactory: (configService: ConfigService) => {
        // The value logged below is undefined'
        console.log(`DB URL: ${configService.get('DB_URL')}`);
        return {
          type: 'mysql',
          host: configService.get('DB_URL'),
          port: 3306,
          username: configService.get('DB_USER'),
          password: configService.get('DB_PASSWORD'),
          database: configService.get('DB_NAME'),
          entities: ['dist/**/*.entity{.ts,.js}'],
          synchronize: false,
          migrations: ['dist/migrations/*{.js}'],
          cli: {
            migrationsDir: 'migrations',
          },
        };
      },
      inject: [ConfigService],
    }),
  ],
  controllers: [AppController],
  providers: [AppService],
})
export class AppModule {}

As noted above, the value retrieved by configService.get('DB_URL') is undefined. Was hoping for any help/advice on how to set up the configuration so that I could read the values in my .env file when starting up the application.