From The Blog: New Google Play Games Services plugin

[bjoern]

@rob

@bjoern, what is the status on your app with regards to alpha test, beta test, release? Is your account an authorized tester? Here is what the engineer had to say:

“I looked at this issue and here are my thoughts. When I started working on this plugin I also got every time isConnected() false in any case until I put the app signed with the correct key into Google Play Console, particularly, into internal test branch of release section. After that, I added my own email addresses into testers list, activated Play Game Services for this app and only then became able to download it from play store. Until I done all of these isConnected() returned false every time. When I installed the test app from Google Play store, everything behaved as expected and isConnected() has returned true.”

My app is set up as an Alpha test with my email as a tester. Maybe something in what he said will give you a clue as to the difference.

Rob

I just tested it the way described above - I uploaded my APK signed with the release key as internal test to Google Play Console, and also made it available for Alpha test. My account is registered as tester for internal tests and for Alpha tests. I installed the Alpha test version of the app on the device from Google Play Store. (My leaderboard and achievements are all in a published state).

I still get the same behavior as described above.