npm install --production ignore my dependencies - node.js

Question

I have this package.json:
{
"private": true,
"scripts": {
"dev": "npm run development",
"development": "cross-env NODE_ENV=development node_modules/webpack/bin/webpack.js --progress --config=node_modules/laravel-mix/setup/webpack.config.js",
"watch": "npm run development -- --watch",
"watch-poll": "npm run watch -- --watch-poll",
"hot": "cross-env NODE_ENV=development node_modules/webpack-dev-server/bin/webpack-dev-server.js --inline --hot --disable-host-check --config=node_modules/laravel-mix/setup/webpack.config.js",
"prod": "npm run production",
"production": "cross-env NODE_ENV=production node_modules/webpack/bin/webpack.js --progress --config=node_modules/laravel-mix/setup/webpack.config.js"
},
"dependencies": {
"cross-env": "^7.0.3"
},
"devDependencies": {
"autoprefixer": "^10.2.6",
"axios": "^0.19",
"browser-sync": "^2.26.14",
"browser-sync-webpack-plugin": "^2.3.0",
"cross-env": "^7.0.3",
"laravel-mix": "^6.0.19",
"less": "^3.13.1",
"less-loader": "^7.3.0",
"lodash": "^4.17.21",
"resolve-url-loader": "^3.1.3",
"vue-template-compiler": "^2.6.14"
}
}
Just for testing how do work NodeJS, NPM, Laravel and Laravel Mix (Webpack) together, I run:
npm install --production (https://docs.npmjs.com/cli/v7/commands/npm-install)
With the --production flag (or when the NODE_ENV environment variable is set to production), npm will not install modules listed in devDependencies.
Actual behavior
When I go to node_modules folder, I don't see any cross-env package there. Moreover the output of the command line is:
$ npm install --production
up to date, audited 1 package in 17s
found 0 vulnerabilities
, meaning no package (in particular: cross-env) was installed.
Expected behavior
cross-env (and only cross-env) would be installed, being part of dependencies, with this command: npm run install --production.
Question
Why does dependencies array seem to be ignored by NPM?

Answer 1

You have cross-env also listed in devDependencies. Dependencies should only be declared in one location. Perhaps npm ignored cross-env as it is listed in devDependencies.

Answer 2

I have found that this occurs even if the dependency is not explicitly listed twice in package.json but is a sub-dependency of a package declared in dependencies. My example:
{
"dependencies": {
"sharp": "^0.26.1" // depends on "color" which depends on "color-convert"
},
"devDependencies": {
"color-convert": "^2.0.1"
}
}
In this example, color-convert will NOT be installed if running npm install --only=production even though it is a dependency of a production dependency (using npm v6.14.14)