Unity3D - Static Action not triggered in WEBGL

Question

I'm stuck with an event not triggered when I run an app on WebGL. It works pretty well when within the Unity Editor, but on browser subscribed methods to the Action aren't being called. Would really nice if I may have some helps.
Here is the Action Class

public static class RestAction
{
    public static Action<double, double> OnSpinDataReadyToSend;
    public static Action<SlotPlayer> OnSlotMachineReady;
}

Where it is being invoked

public class GameController
{
    void Start()
    {
        RestAction.OnSlotMachineReady?.Invoke(this.MPlayer);
    }
}

And then, the concerned methods

    private void OnEnable()
    {
        RestAction.OnSlotMachineReady += getPlayerInfo;
        SlotPlayer.ChangeCoinsEvent += UpdateBalance;
    }

    private void OnDisable()
    {
        SlotPlayer.ChangeCoinsEvent -= UpdateBalance;
        RestAction.OnSlotMachineReady -= getPlayerInfo;
    }

    private void getPlayerInfo(SlotPlayer player)
    {
        this.MPlayer = player;
        Debug.Log("player number = "+PlayerPrefs.GetString(Player.PlayerKey));
        StartCoroutine(RestClient.Instance.GetPlayerInfo(PLAYER_INFO,PlayerPrefs.GetString(Player.PlayerKey),player.webAPIUpdateCoins));
    }

    private void UpdateBalance(int coins)
    {
        Debug.LogWarning("coins : "+coins);
        StartCoroutine(RestClient.Instance.SendSpinData(WEB_URL,coins,randomCallback));
    }