Hi there,
Can you try if something in the Troubleshooting section of the documentation is helpful? In particular, can you check if a blank Ionic application (using Ionic 5) works in your environment?
If the problem persists, you can look at the logs if you are running the apk in an emulator (or a device connected to your computer) and visit chrome://inspect in chrome. That should give you an idea of why the app is not launching.