Polymorphic model only working on one model

I currently have a polymorphic relationship using a model like so:

The model is called Productable In the model I have:

public function productable()
{
  return $this->morphTo();
}

I have another model called Product that has access to the Productable model like so:

public function productDetails()
{
  return $this->morphMany(Productable::class, 'productable');
}

This works as expected and I can create a record in the Productable table like so:

  $p = new Product;
  $p->product_name = $request->product_name;
  $p->product_type = $request->product_type;
  $p->category_id = $request->product_category;
  $p->description = $request->product_description;

  $p->save();

  $p->productDetails()->create([
    'product_id' => $p->id,
  ]);

However the issue is I have another model called Media which also has:

public function productDetails() { return $this->morphMany(Productable::class, 'productable'); }

On that model I attempt to write a record like so:

              $pMedia = new Media;
              $pMedia->productDetails()->create([
                'product_id' => $p->id,
                'productable_id' => $value,
              ]);

The error I get is:

Integrity constraint violation: 1048 Column 'productable_id' cannot be null (SQL: insert into `productables` (`product_id`, `productable_id`, `productable_type`, `updated_at`, `created_at`) values (38, ?, App\Models\Media, 2021-03-04 18:46:51, 2021-03-04 18:46:51))

What am I doing wrong here? Shouldn't I be to write to Media in the same way? I'm wondering what I'm missing.