I\'m trying to utilize the Review API (Play Core library 1.8.0) from Google which was just released yesterday. See https://developer.android.com/guide/playcore/in-app-review
Just to be clear you are not using com.mypackage right?
2020-08-06 16:01:29.318 29618-29618/? I/PlayCore: UID: [10409] PID: [29618] ReviewService : requestInAppReview (com.mypackage)
Ensure that the appId used is the one that it's "owned" (aka installed by) by the selected account in the Play Store in the device.
I believe the test guide (https://developer.android.com/guide/playcore/in-app-review/test) is clear in terms of how to test it given the different requirements.
My tips:
PS: You could test also the Internal App Sharing.