Your game has incorrectly implemented the following Play Games services: Achievements

Question

I have read the other posts on here but cannot find an answer. I have the alert:

Your game has incorrectly implemented the following Play Games services: Achievements

That links to here: https://support.google.com/googleplay/android-developer/answer/3433208#games_alerts which states:

Achievements: This game has created achievements in the Play Console but never calls the SDK's unlock methods. This approach is discouraged because it could result in a poor user experience.

I have checked here https://developers.google.com/games/services/checklist#2_achievements and I follow the one and only required guideline, plus nearly all the others. I have 23 achievements, all are attainable in the game and I use this code to unlock them:

if(signedIn == true) {
    Games.getAchievementsClient(this, GoogleSignIn.getLastSignedInAccount(this)!!)
        .unlock(getString(R.string.achievement_100))
}

the string is in the games-ids.xml and all is working, people have been unlocking the achievements. Is there anything else I can/should do?

Are google likely to take this further?

Thanks