Why does neither hot reloading nor live reloading take effect on this React Native app?

Question

Why does the neither hot nor live reloading take any effect on this React Native app?

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Abstract

I've recently started working as a contractor on developing a rather seasoned React/React Native app (logic is being shared for both mobile version of the website and native application) for a company which does not rely on expo. Having always worked with the mentioned tool, the transition to in-house methods of dealing with React Native gives me some headache.

Setting the emulator to settings that used to work for me (having manually turned on hot reloading on emulator is the closest I get to expo) do not affect the app in any way other than sending a notification that hot reload took place.

Moreover, I assume that the issue might be platform-specific. The lead front end dev works on Windows with the same project/dev environment setup and experiences no trouble.

On starting the app

To launch the app, I'm using custom npm run android script (depending on gulp), which goes as follows:

npm run android

• npm run buildRN && npm run rnAndroid
  • buildRN: npm run dropOldBabel && npm run buildNF && npm run rnLink && npm run buildImagesList
    • dropOldBabel: cd node_modules && rm -f react-pure-render/.babelrc redux-devtools-themes/.babelrc base16/.babelrc react-json-tree/.babelrc form-schema-validation/.babelrc && cd ..
    • buildNF: gulp buildNativeFiles
    • rnLink: node node_modules/react-native/local-cli/cli.js link
    • buildImagesList: gulp generateImagesList
  • rnAndroid: node node_modules/react-native/local-cli/cli.js run-android

After going through generating images, it starts the JS server, fires up Gradle and installs the app on target device (my Android emulator).

App targets running on localhost on port 8081, therefore adb -s emulator-5554 reverse tcp:8081 tcp:8081 command is being issued. I suspect that this port forwarding might somehow be the one to blame for the issue, although I don't know how to back this claim up.

Then the app starts with adb -s emulator-5554 shell am start -n com.firm.name/com.firm.name.MainActivity command and node console happily shows Starting: Intent { cmp=com.firm.name/.MainActivity }.

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On the development process

As experience with expo taught me, it shall be enough to make changes and save the file for the change to take effect. However, this is not the case.

Saving a file does nothing except informing me via emulator that hot reloading took place. Beside this toast notification I get nothing. Moreover, turning on Live Reload changes nothing; the change is applied iff I restart the app completely by stopping the server and invoking npm run android.

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Platform

OS

• elementary OS 6 Odin (Built on Ubuntu 20.04.2 LTS)

Node

• npm -v 6.4.1
• node -v 10.14.1

React Native

• react-native-cli: 2.0.1
• react-native: 0.59.10

Android Emulator

• Android emulator version 30.8.4.0 (build_id 7600983)
• Nexus 5X image

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Summary

To sum it up - what could possibly cause such behavior?

Why does the code not change until restart while the emulator clearly notices the change?

Why does it only happen on my platform, not on Windows 10?