Firebase Crashlytics not reporting crashes when manually enabled

Use following dependencies for android.
Paste it into build.gradle app:

implementation('com.crashlytics.sdk.android:crashlytics:2.9.6@aar') {
transitive = true
}

Upgrade it from 2.9.5 to 2.9.6.
It works for me.

There is an issue with Firebase Crashlytics 2.9.7 preventing opt-in reporting as described in the documentation to work: the start of Crashlytics from code will not be performed. For the time being downgrading to 2.9.6 will enable your code to work properly.

Please follow this answer https://stackoverflow.com/a/59906454/6743289

For those wish to use crashlytics for their android app who haven't been using crashlytics of fiber.io, there are certain changes in the way you FirebaseApp is initialized which you will find in the above link.