Ionic push with phonegap-plugin-push

I have an app with cordova-push-plugin (1.8.4) compiled with the old dashboard in December and push notifications work well (android). Now, I made small changes in the app and I compiled the app in the new pro dashboard in debug release. I took the apk and installed it on the smartphone: everything works fine, except for the push notifications. The server sends push notifications and logs return ‘success’ from the google server, but nothing happens on the smartphone.

Where can I investigate to understand the problem?