Understanding this code snippet, debug a $query

I have the task of debugging some code that isn't mine and quite frankly I have no clue what is happening in this code. The situation is that this code works for everyone else except a specific provider and I don't know why, and I need to find out what is happening.

This is the method in my controller

public function postData(Request $request)
    {
        $query = Product::query();
        $query->whereHas('brand', function ($query) use($request) {
            $query->whereHas('vendor', function ($query) use($request) {
                $query->where('id', $request->id);
            });
        });

        if ($request->has('vendor_id')) {
            $country = session('country');

            $query->whereHas('countryProducts', function ($query) use ($country) {
                $query->where('country_id', $country['id']);
            });
            $query->with([
                'brand.vendor',
                'countryProducts' => function ($query) use ($country) {
                    $query->where('country_id', $country['id']);
                }
            ]);
        } else {
            $query->with([
                'brand.vendor'
            ]);
        }
        if ($request->has('range1')) {
            $query->whereHas('countryProducts', function ($query) use ($request) {
                $query->whereBetween('price', [$request->range1, $request->range2]);
            });
        }
        if ($request->brand) {
            $query->whereIn('brand_id', $request->brand);
        } else {
            $query->with([
                'brand.vendor'
            ]);
        }

        if ($request->size) {
            $query->whereHas('sizes', function ($query) use ($request) {
                $query->whereIn('id', $request->size);
            });
        }

        if ($request->has('term')) {
            $term = '%' . $request->term . '%';
            $query->where(function ($query) use ($term) {
                $query->where('code', 'like', $term)
                    ->orWhere('sku', 'like', $term)
                    ->orWhere('description_spanish', 'like', $term)
                    ->orWhereHas('brand', function ($query) use ($term) {
                        $query->where('name', 'like', $term);
                    })
                    ->orWhereHas('countryProducts', function ($query) use ($term) {
                        $query->where('price', 'like', $term);
                    });

            });
        }

        if ($request->has('sort')) {
            list($sortCol, $sortDir) = explode('|', $request->sort);
            if ($sortCol == 'price') {
                $country = session('country');
                $request->request->remove('sort');

                $query->select([
                    'products.*',
                    'country_product.price as price'
                ])
                    ->join('country_product', function ($join) use ($country) {
                        $join->on('products.id', '=', 'country_product.product_id')
                            ->where('country_product.country_id', $country['id']);
                    })
                    ->orderBy('price','asc');
            }
        }

        if ($request->has('paginate')) {
            return TableVue::arrayOf($request, $query);
        } else {
            return $query->get();
        }
    }

The TableVue arrayOf method

static function arrayOf(Request $request, Builder $query, array $searchField = []) {
        // handle sort option
        self::filters($request, $query, $searchField);
        $perPage = $request->has('per_page') ? (int) $request->per_page : null;
        $pagination = $query->paginate($perPage);
        $pagination->appends([
            'sort' => $request->sort,
            'filter' => $request->term,
            'per_page' => $request->per_page
        ]);

        return response()->json($pagination);
    }

This code is supposed to return a list of products for the provider but it's returning 0 when I know for a fact there are products to be returned (they're visible in the db).

This is the response in the browser console for the provider getting to products

Response {url: "/provider/data?page=1&paginate=true&per_page=25&vendor_id=5&range1=0&range2=7015&id=5", ok: true, status: 200, statusText: "OK", headers: Headers, …}
body: {current_page: 1, data: Array(0), first_page_url: "http://dev.sondel.com/provider/data?per_page=25&page=1", from: null, last_page: 1, …}
bodyText: "{"current_page":1,"data":[],"first_page_url":"http:\/\/dev.sondel.com\/provider\/data?per_page=25&page=1","from":null,"last_page":1,"last_page_url":"http:\/\/dev.sondel.com\/provider\/data?per_page=25&page=1","next_page_url":null,"path":"http:\/\/dev.sondel.com\/provider\/data","per_page":25,"prev_page_url":null,"to":null,"total":0}"
headers: Headers {map: {…}}
ok: true
status: 200
statusText: "OK"
url: "/provider/data?page=1&paginate=true&per_page=25&vendor_id=5&range1=0&range2=7015&id=5"
data: (...)
__proto__: Object

This is the response for a provider that is correctly displaying the products

body: {current_page: 1, data: Array(25), first_page_url: "http://dev.sondel.com/provider/data?per_page=25&page=1", from: 1, last_page: 60, …}
bodyText: "{"current_page":1,"data":[{"id":542,"code":"VTFGR","sku":"VTFGR", ..."
headers: Headers {map: {…}}
ok: true
status: 200
statusText: "OK"
url: "/provider/data?page=1&paginate=true&per_page=25&vendor_id=3&range1=0&range2=7015&id=3"
data: Object
__proto__: Object

I don't know where to start on figuring out why this is happening?

Any ideas?