Pivot table return null using laravel 5.7.*

I have two models named: League ans User

There's a pivot table named: league_user contains this structure:

id
user_id
league_id
joined_at
rank
payment_id
created_at
updated_at

This is my Models:

class League extends Model
{
    protected $fillable = [
        'name', 'capacity', 'is_open', 'started_at', 'finished_at', 'is_free', 'price', 'level', 'user_id', 'closed_by', 'edited_by'
    ];

    protected $hidden = [];


    /*
     * User Relationship
     */
    function user()
    {
        return $this->belongsTo(User::class);
    }


    /*
     * Editor Relationship
     */
    public function editor()
    {
        return $this->belongsTo(User::class, 'edited_by');
    }

    /*
     * All users Relationship
     */
    public function all_users()
    {
        return $this->belongsToMany(User::class)->withTimestamps()->withPivot('rank', 'joined_at');
    }
}

And User Model:

class User extends Authenticatable
{
    use Notifiable;

    /**
     * The attributes that are mass assignable.
     *
     * @var array
     */
    protected $fillable = [
        'name', 'family', 'email', 'mobile', 'password', 'username', 'team', 'email_verified_at', 'mobile_verified_at', 'role_id'
        ];

    /**
     * The attributes that should be hidden for arrays.
     *
     * @var array
     */
    protected $hidden = [
        'password', 'remember_token',
    ];


    /*
     * Roles ralationship
     */
    public function role()
    {
        return $this->belongsTo(Role::class);
    }

    /*
     * Question Relationship
     */
    public function questions()
    {
        return $this->hasMany(Question::class);
    }

    /*
     * League Relationship
     */
    public function leagues()
    {
        return $this->hasMany(League::class);
    }


    /*
     * Setting Relationship
     */
    public function setting()
    {
        return $this->hasOne(UserSetting::class);
    }


    /*
     * All Leagues that User Joined
     */
    public function all_leagues()
    {
        return $this->belongsToMany(League::class)->withTimestamps()->withPivot('rank', 'joined_at');
    }

}

Now when I want to access to the rank or joined_at in my pivot table, it seems something is wrong or at least I'm doing that in a wrong manner.

I tried this:

foreach ( $leagues as $league )
{
    $pivot[] = $league->pivot;
}

dd($pivot);
}

to check my pivot behavior, and I did check $league->pivot->rank or $league->pivot->joined_at either, but pivot table seems to be null!

Can any one tell me what's wrong in my code?

I saw these links:

laraveldaily

laracast

laravel documentation

and...

via Chebli Mohamed