Google Play Game Services : CommitBlocking does not commit

I was doing a little game using cocos2d-x for android. I am currently struggling to implement Cloud Save for my game. The only problem left is that it does not commit.

The GPGS API I am using is C++. Just scroll down to the commitblocking there.

//using sample codes from Google.
game_services->Snapshots().Open
(
    "some_save_file",
    gpg::SnapshotConflictPolicy::MANUAL,
    [this, &save](gpg::SnapshotManager::OpenResponse const& response)
    {
        LOGI("Saving snapshot");
        if(gpg::IsSuccess(response.status))
        {
            LOGI("Open success");
            gpg::SnapshotMetadata metadata = response.data;
            if (response.conflict_id != "")
            {
                //Conflict detected
                //Settle conflict
            }

            LOGI("Getting PNG data");
            //get cover image data
            //some code to get png data in to png_vector

            LOGI("Building snapshot builder");
            //setting up the builder
            gpg::SnapshotMetadataChange::Builder builder;
            gpg::SnapshotMetadataChange metadata_change =
                    builder
                    .SetDescription("Recall Save File")
                    .SetCoverImageFromPngData(png_vector)
                    .Create();

          LOGI("Commiting");
          // Save the snapshot.
          // This is the part that does not work !!!!!
          gpg::SnapshotManager::CommitResponse commitResponse =
              game_services->Snapshots().CommitBlocking(gpg::Timeout(3000), response.data, metadata_change, save);

          if (IsSuccess(commitResponse.status))
            CSH_LOGI("Saved game");
          else
            CSH_LOGI("Saved game failed error: %d", commitResponse.status);
    }
);

When compiled and running on phone :

    06-25 16:51:47.405: V/GamesNativeSDK(10717): Snapshot was not committed, discarding.
    06-25 16:51:47.410: V/GamesNativeSDK(10717): Snapshot discard complete.

I had tried with Commit(), which crash the game, and CommitBlocking() with no timeout, it doesn't commit too.

I spent almost a week on this problem looking at the documentation and samples. So, anyone met this problem before ? If do, do share with me how to solve it.

Thanks.