Sqlite in Unity for Android

I am developing a .APK in Unity, where I have a BD in SQLite .

When doing tests within the Unity environment everything works perfectly, but when exporting it to .APK and testing it on my phone, after executing 2 queries in a row the program "crashes" I put it in quotation marks since the interface keep responding.

SQLite code of the query;

public bool UsuarioCorrecto(string nombre, string contra)
{
    int code = 0;

    using (SqliteConnection con = new SqliteConnection(connection))
    {
        con.Open();
        using (SqliteCommand cmd = new SqliteCommand())
        {
            cmd.CommandText = @"select nombre from Usuarios where nombre like @nombre and contrasena like @contrasena";
            cmd.Connection = con;
            cmd.Parameters.Add(new SqliteParameter("@nombre", nombre));
            cmd.Parameters.Add(new SqliteParameter("@contrasena", contra));
            using (SqliteDataReader reader = cmd.ExecuteReader())
            {
                if (reader.HasRows)
                {
                    code = 1;
                }
                else { code = 0; }
            }
        }
    }

    if (code == 1)
    {
        return true;
    }
    else
    {
        return false;
    }

}

Code to authenticate a user;

public void deleteUltimaCon()
{
    using (SqliteConnection con = new SqliteConnection(connection))
    {
        con.Open();
        using (SqliteCommand cmd = new SqliteCommand())
        {
            cmd.CommandText = @"delete from ultimaCon";
            cmd.Connection = con;
            cmd.ExecuteNonQuery();
        }
    }
}

public void Conectar_Click()
{
    if (conectarDB())
    {
        #if UNITY_ANDROID
        dialog.showDialog("Usuario correcto!");
        #endif
        db.deleteUltimaCon();
        db.anadirUltCon(nombre.text);
        MensajeConectar.text = "Exito..";
        ProjectVars.Instance.StringActiveBetweenScenes = nombre.text;
        SceneManager.LoadScene("menJugador");
    }
    else
    {
        mostrarTextAut();
        MensajeConectar.text = "Fallo de autentificación";
        Invoke("ocultarTextAut", 1.5f);
    }
}

Testing with messages the execution stays on the line where it says db.deleteUltimaCon();

How could I fix it so that the application does not get "hung up"?