Laravel - Many to Many Relationship & Policies

I'm relatively new to Laravel and am trying to learn as fast as I can but recently came across an issue that I just can't seem to shake.

I have 3 tables with the relevant fields for this post:

1. Users - id
2. Shipment_User - shipment_id, user_id
3. Company_User - company_id, user_id
4. Companies - id

Because of complexities, I have been suggested by a friend to handle the following through a policy, rather than middleware (however, if one of you has a suggestion, I'm willing to look into it of course :)). Anyways, what I would like to do is have a policy (which I will lay out the current one I have below) where if a user is attached to any number of companies, they can see all of the shipments attached to those companies (and on my Shipment, User and Company models, I do have the relationships laid out as "belongsToMany").

So assume the following

Shipment #|Company ID(pivot table: company_shipment)

1 | 1

2 | 1

3 | 2

4 | 3

Then User #1, who is associated through the pivot table (company_user) to companies 1 and 2, can see shipments 1, 2, and 3, but not 4.

Here is my ShipmentPolicy that I have created so far:

<?php



namespace App\Policies;

use App\User;
use Auth;
use App\Shipment;
use App\Company;
use Illuminate\Auth\Access\HandlesAuthorization;

class ShipmentPolicy
{
    use HandlesAuthorization;

/**
 * Determine whether the user can view the shipment.
 *
 * @param  \App\User  $user
 * @param  \App\Shipment  $shipment
 * @return mixed
 */
public function view(User $user, Shipment $shipment)
{
    $user_company = Auth::user()->companies()->pluck('id');
    $shipment_company = $shipment->companies->pluck('id');
    return $shipment_company == $user_company;  

}

/**
 * Determine whether the user can create shipments.
 *
 * @param  \App\User  $user
 * @return mixed
 */
public function create(User $user)
{
    //
}

/**
 * Determine whether the user can update the shipment.
 *
 * @param  \App\User  $user
 * @param  \App\Shipment  $shipment
 * @return mixed
 */
public function update(User $user, Shipment $shipment)
{
    //
}

/**
 * Determine whether the user can delete the shipment.
 *
 * @param  \App\User  $user
 * @param  \App\Shipment  $shipment
 * @return mixed
 */


 public function delete(User $user, Shipment $shipment)
    {
        //
    }
}

Now, my problem arises from the issue that if a user is added to one company, they can view the shipments just fine, however, if they are added to 2 (which is as far as I bothered to test), it fails and it returns an error.

So my questions are:

1. What must I change in how I am handling the set-up of this current policy, and
2. Would there be a better way of handling this issue rather than policies, or with something else in conjunction with policies?

Thanks in advance for any help anyone can provide.

Thanks!! Chase