Signed apk shows a black screen, while debug version shows just fine

Question

Working with debug build variant, my app works just fine. However, when I sign the app and install it, it starts with a black screen. This is what I have in build.gradle:

    buildTypes {
    release {
        minifyEnabled true
        debuggable false
        proguardFiles getDefaultProguardFile('proguard-android.txt'),
                'proguard-rules.pro'
    }

    debug {
        minifyEnabled false
        debuggable true
        proguardFiles getDefaultProguardFile('proguard-android.txt'),
                'proguard-rules.pro'
    }
}

Weird thing is, if i set debuggable true in release, there's no black screen and the app works just fine again. But the problem is I cannot publish an app with debuggable flag set to true.

I'm completely stuck and could not find any similar issue. Any help would be really appreciated.

As I said, I cannot even debug with the release version, since the problem happens when debuggable is false.