Laravel Voyager Undefined property in Models while creating an entry

I have a model named Orders which belongsTo a Payment Method. The relationship is mentioned like this

public function payment_method() {
    return $this->belongsTo(PaymentMethod::class, 'payment_method');
}

I am using Laravel Voyager for Admin UI. I have created a relationship between the two in voyager. When I access orders, view orders, update orders, delete orders work fine. But when I create an order I get the following error

Undefined property: AppModelsOrder::$payment_method (View: /opt/bitnami/projects/project/vendor/tcg/voyager/resources/views/formfields/relationship.blade.php

I think this is because of a custom foreign key ‘payment_method’ but this is only causing problems with voyager and I don’t know why and how to resolve this. It works fine through artisan and API’s