workbox: Workbox doesn't cache in iOS standalone

Library Affected: workbox-sw workbox-webpack-plugin

Browser & Platform: iOS 11.4

Issue or Feature Request Description: I trying to build a PWA that have the offline capability. I’m using workbox-webpack-plugin with InjectManifest class. The app runs well on Safari/Chrome (MacOS and iOS) under both online and offline condition. When I added to the app to home screen from Safari (iOS) and turn off internet connection, I got No connection page from Safari. I tried to debug from Safari but there are no error messages.

App URL: https://nordot-pwa.herokuapp.com/ Webpack config:

new InjectManifest({
      swSrc: path.resolve(paths.appSrc, "sw.js"),
      swDest: "service-worker.js",
      // Don't precache sourcemaps (they're large) and build asset manifest:
      exclude: [/\.map$/, /^(?:asset-)manifest.*\.js(?:on)?$/]
})

Sw.js:

console.log("Service worker is running!");

workbox.skipWaiting();
workbox.clientsClaim();

workbox.routing.registerNavigationRoute("/index.html", {
  whitelist: [/^(?!\/__).*/]
});

// Background sync for tracking post api
const bgSyncPlugin = new workbox.backgroundSync.Plugin("trackingQueue", {
  maxRetentionTime: 24 * 60 // Retry for max of 24 Hours
});
workbox.routing.registerRoute(
  /\/api\/.*\/*.json/,
  workbox.strategies.networkOnly({ plugins: [bgSyncPlugin] }),
  "POST"
);

workbox.precaching.precacheAndRoute(self.__precacheManifest);

When reporting bugs, please include relevant JavaScript Console logs and links to public URLs at which the issue could be reproduced.