Cannot use snapshots without enabling the 'Saved Game' feature in the Play console using Flutter

Question

The error seems pretty self-explanatory when trying to save games in Google Play Games, but I have this already enabled. Google's documentation says it can take up to 24h to activate, but I activated this days ago and I constantly get this error, no matter how long I wait. Looking in google for extra configuration, I don't find anything else.

I'm using Flutter:

Future<void> saveGame() async {
    var data = '{number: 5}';

    await SaveGame.saveGame(data: data, name: "slot1");
  }