Angular 8 web app failing to deploy to heroku - node.js

Question

I feel like my Angular app is fully setup for deploying to Heroku, but for some reason it just hangs during the build process and never continues - eventually resulting in a Build Failed message, but no logs.
Here is an excerpt of the heroku logs --tail:
-----> Build
Detected both "build" and "heroku-postbuild" scripts
Running heroku-postbuild
> flux-admin#1.0.0 heroku-postbuild /tmp/build_d18bae1ef2310aacfb6851eddfeab6d1
> ng build --prod
Generating ES5 bundles for differential loading...
ES5 bundle generation complete.
chunk {0} runtime-es2015.edb2fcf2778e7bf1d426.js (runtime) 1.45 kB [entry] [rendered]
chunk {0} runtime-es5.edb2fcf2778e7bf1d426.js (runtime) 1.45 kB [entry] [rendered]
chunk {1} main-es2015.b5ce220634282bd1233e.js (main) 1010 kB [initial] [rendered]
chunk {1} main-es5.b5ce220634282bd1233e.js (main) 1.08 MB [initial] [rendered]
chunk {2} polyfills-es2015.2987770fde9daa1d8a2e.js (polyfills) 36.4 kB [initial] [rendered]
chunk {3} polyfills-es5.df1101cc1e7b588877f8.js (polyfills-es5) 122 kB [initial] [rendered]
chunk {4} styles.c1cdb3f05888558b2d70.css (styles) 60.6 kB [initial] [rendered]
Date: 2019-11-23T15:43:44.636Z - Hash: 80ca71603894ea5db348 - Time: 114953ms
That is where it just hangs.
Here is my package.json file:
"name": "flux-admin",
"version": "1.0.0",
"scripts": {
"ng": "ng",
"start": "node server.js",
"build": "ng build",
"test": "ng test",
"lint": "ng lint",
"e2e": "ng e2e",
"heroku-prebuild": "",
"heroku-postbuild": "ng build --prod"
},
"private": true,
"dependencies": {
"#angular/animations": "~8.2.14",
"#angular/cdk": "~7.3.3",
"#angular/cli": "~8.3.19",
"#angular/common": "~8.2.14",
"#angular/compiler": "~8.2.14",
"#angular/compiler-cli": "^8.2.14",
"#angular-devkit/build-angular": "~0.803.19",
"#angular/core": "~8.2.14",
"#angular/forms": "~8.2.14",
"#angular/material": "^7.3.3",
"#angular/platform-browser": "~8.2.14",
"#angular/platform-browser-dynamic": "~8.2.14",
"#angular/router": "~8.2.14",
"core-js": "^2.5.4",
"path": "^0.12.7",
"rxjs": "~6.5.3",
"express": "^4.17.1",
"rxjs-compat": "^6.4.0",
"tslib": "^1.9.0",
"typescript": "~3.5.3",
"zone.js": "~0.9.1"
},
"devDependencies": {
"#angular/cli": "~8.3.19",
"#angular/compiler-cli": "^8.2.14",
"#angular/language-service": "~8.2.14",
"#types/jasmine": "~2.8.8",
"#types/jasminewd2": "~2.0.3",
"#types/node": "~8.9.4",
"codelyzer": "^5.0.1",
"enhanced-resolve": "^3.3.0",
"jasmine-core": "~2.99.1",
"jasmine-spec-reporter": "~4.2.1",
"karma": "~4.0.0",
"karma-chrome-launcher": "~2.2.0",
"karma-coverage-istanbul-reporter": "~2.0.1",
"karma-jasmine": "~1.1.2",
"karma-jasmine-html-reporter": "^0.2.2",
"protractor": "~5.4.0",
"ts-node": "~7.0.0",
"tslint": "~5.11.0",
"typescript": "~3.5.3"
},
"engines": {
"node": "11.10.0",
"npm": "6.13.1"
}
My server.js file is the following:
//Install express server
const express = require('express');
const path = require('path');
const app = express();
// Serve only the static files form the dist directory
app.use(express.static(__dirname + '/dist/flux-admin'));
app.get('/*', function(req,res) {
res.sendFile(path.join(__dirname+'/dist/flux-admin/index.html'));
});
// Start the app by listening on the default Heroku port
app.listen(process.env.PORT || 8080);
Just in case I also added a Procfile:
web: node server.js
When I try and run ng build --prod --aot locally - it does complete successfully, so it just seems to not go onto the next step in the heroku deployment process (which I believe would be the start script).
Anything obvious wrong with my setup?
UPDATE
After multiple attempts to try and get this deployed - I ended up degrading back to Angular 7, and it deployed with no problem!
I believe the issue must stem with the new way the ng build --prod --aot is run in Angular 8, but I am not at all sure why or what the cause is. So for now, I will just continue using Angular 7 and post a bug report.