Google Maps not loading only on build -- prod (--release)

Friends, I implemented basic Google Maps functionality from Ionic 2 documentation as is (https://ionicframework.com/docs/v2/native/google-maps/). When I execute

ionic run android

It shows map and I see in my google developer console API hits. BUT if I run

ionic build android --prod

It does not shows map and there is no API hits.
cordova-plugin-whitelist is installed
Device the same for run and build - Nexus 5
What can block API hits only for build?

You are not only changing from run to build but also adding --prod.
Did you try run android --prod to see if it works then?

This is works normal. Maps shows normally

ionic build android

I suppose Google Maps ssl is ok) So why maps does not work with --prod?

So I found solution. I signed apk and built with --release flag
ionic build android --release
Works normally.

By the way
ionic build android --prod

Does not run at all, application stacks with splash screen. Anyone can explain that?