Blank map when I sign

I use Android Studio 3.0.1 generated the key (when it is generated there is no way to define if it is debug or release) I changed my "key" I changed the "Buid variants" to "freeRelease" but continue the map blank when I sign , is there any more items to check?

My Gradle:

   defaultConfig {
        applicationId "br.com.xxx.xxx"
        minSdkVersion 15
        targetSdkVersion 26
        versionCode 27
        versionName "2.7"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
        debug {
        }
    }
    flavorDimensions "default"
    productFlavors {
        free {
            applicationId "br.com.xxx"
            applicationIdSuffix '.free'
        }
        paid {
            applicationIdSuffix '.paid'
        }
    }