Build anfroid with --release flag or not?

When I create the .apk or .aab bundle, using --release, the aplication fails to set value of radio button group. This not occurs when only I use Ionic build android --prod

When I build the app whithout --release, signing proccess appears not work, bacause Google says the Sign is not valid.

In order to publicate the app in Google Play, I must mandatory to use --release flag?

Using Ionic 5 and Cordova.