Android : ShowAchievementsUI(); don't want to appear on Android

I am using the official PlayGameServices plugin for Unity, and have been following the installation to the point. Authentication seems to work like a charm, but when I want to do the ShowAchievementsUI();, nothing happends. No UI, no errors, no crashes.

Ive been googling around for a while, it seems other people have hit this problem, but with no solution in sight.

My code at the moment is :

using GooglePlayGames;
using UnityEngine.SocialPlatforms;

void Start() {
    PlayGamesPlatform.DebugLogEnabled = true;
    PlayGamesPlatform.Activate();
    LoginSocialGamecenter();
}


public static void LoginSocialGamecenter() {
    if (Social.localUser.authenticated) {
        Social.ShowAchievementsUI (); Debug.Log("Pancakes!");
        return;
    }
}

And "Pancakes!" comes out perfectly. Authentication UI on first install also shows up nicely. It fails on all devices I have, but shows up perfectly on Android.

According to the documentation, it should work as described:

Showing the Achievements UI

To show the built-in UI for all leaderboards, call Social.ShowAchievementsUI.

using GooglePlayGames;
using UnityEngine.SocialPlatforms;
...
// show achievements UI
Social.ShowAchievementsUI(); 

This will show a standard UI appropriate for the look and feel of the platform (Android or iOS).