Watchify does not recognise changes with transform (babelify)

[kontur]

With a "stripped" package.json looking like this:

{
  …
  "scripts": {
    "js": "watchify src/app.js -t [ babelify --presets [ @babel/preset-env ] ] -o assets/js/app.js"
  },
  "devDependencies": {
    "@babel/cli": "^7.7.4",
    "@babel/core": "^7.7.4",
    "@babel/preset-env": "^7.7.4",
    "babelify": "^10.0.0",
    "watchify": "^3.11.1"
  }
}

…watchify runs fine once, but no changes to src/app.js or any included dependencies are triggering a new build. The required dependencies in the app are minimal (just a scaffold atm). It just goes into limbo.