If you’ve managed to configure PoLo for local builds, there are some minor changes for Android builds.
You no longer need to call npm run android -- --mode alphaDebug. A simple npm run android should work.
This also means that just pressing a in a dev server console (what you get when you run npm start) should start an Android build.
Also, it’s a good idea to do a full clean build every month or so. There are instructions in the README on how to do so.