How to save game data to the cloud using gdx-gamesvcs?

I want to implement Google Play Games Services in my game on the libgdx engine. I tried using gdx-gamesvcs for this. But I am having trouble saving data. I understood from the example that one value is being saved, not the entire state of the game. So I decided to check it out: save and load one value using gsClient.loadGameState and gsClient.saveGameState. I deliberately deleted the game data from the device. But as a result, not only the test value changed, but many others as well. I thought that the state of the entire game is being saved, but the values ​​obtained do not fit into the logic of the game and could not be obtained in it.
How should I use this tool and is it worth it at all, or is it better to use what libgdx itself offers?
Here is a piece of code:

if (gsClient.isSessionActive()) {
            try {
                gsClient.saveGameState("data", intToByteArray(testValue), 0, null);
            } catch (UnsupportedOperationException unsupportedOperationException) {
}


if (gsClient.isSessionActive()) {
            try {
                gsClient.loadGameState("data", new ILoadGameStateResponseListener() {
                    @Override
                    public void gsGameStateLoaded(byte[] gameState) {
                        if (gameState != null) {
                            setTestValue(bytesToInt(gameState));
                        }
                    }
                });
            } catch (UnsupportedOperationException unsupportedOperationException) {
            }
}

UPD
Yes, saving occurs both to the cloud and to the device, for saving to the device I use Preferences. I have a Google account login button in the game, it works, I have repeatedly seen this standard bar of my account level, which appears at the top when I log in. Everything is set up in the developer console too, I have an id for achievements and leaderboards. In code, I work with the client like this (In the create() method):

public IGameServiceClient gsClient;

if (gsClient == null) {

            gsClient = new MockGameServiceClient(1) {
                @Override
                protected Array<ILeaderBoardEntry> getLeaderboardEntries() {
                    return null;
                }

                @Override
                protected Array<String> getGameStates() {
                    return null;
                }

                @Override
                protected byte[] getGameState() {
                    return new byte[0];
                }

                @Override
                protected Array<IAchievement> getAchievements() {
                    return null;
                }

                @Override
                protected String getPlayerName() {
                    return null;
                }
            };
        }
        gsClient.setListener(this);
        gsClient.resumeSession();

Next is loading.
The exception is not caught, I removed it and everything works as before.

Well, libgdx offers no built-in cloud-save, it is hard to use it for that.

You should in any case save to local AND to cloud, as the cloud is not very fast to load its state.

I can see no problem in your code besides the fact that you swallow an UnsupportedOperationException that is thrown if you did not activate cloud save feature. So the interesting question is: what happens if you don't swallow the exception, and did you intialize GpgsClient with cloud save enabled? Are you really logged in to Gpgs, and is the feature also activated in your developer console?

The main problem was that gameState was null, this arose due to the fact that you had to wait 24 hours after enabling the save function in the developer console, and the advice on clearing the memory of google play games on the test device did not help. After a while gameState began to pass the existing values, but I started having problems with the graphics flow, probably due to the asynchronous loading.