this is my situation - GooglePlayGamesPlugin-0.9.39a.unitypackage - unity 5.6.0f - not using App Signing in google play console
when I call login functions error "Starting Auth Transition. Op: SIGN_IN status: ERROR_NOT_AUTHORIZED" is occurred
all login function has the same result - Social.localUser.Authenticate - PlayGamesPlatform.Instance.Authenticate
how to solve it?