Grid not receiving array data from DataProvider

Question

In my module, I use the Listing (grid) UI component to render data from an array. The data for the grid is provided by a DataProvider.php class getData() method.
For some reason, when I use a simple testing array, the data is properly rendered. When I use the actual array that I want to use, the grid displays the message: We couldn't find any records.

I am very sure that both arrays have the same format, so both should work. Using print_r() to print the arrays, they look identical in format. gettype() returns array for both arrays.

My DataProvider.php:

public function getData()
    {
        $orderIds = $this->_registry->registry("orderids");

        foreach ((array)$orderIds as $orderId) {

            $order = $this->_order->load($orderId);

            $orderInfo[] = [ // This array doesn't work
                "entity_id" => $order->getId(),
                "customer_firstname" => $order->getCustomerFirstname(),
                "customer_lastname" => $order->getCustomerLastname(),
                "customer_email" => $order->getCustomerEmail(),
            ];
        }

        $test[] = [ // This test array works
            "entity_id" => 1,
            "customer_firstname" => "Foo",
            "customer_lastname" => "Bar",
            "customer_email" => "foo@bar.com",
        ];

        $data = [
            'totalRecords' => count($orderInfo), // $test works, $orderInfo doesn't
            'items' => array_values($orderInfo), // $test works, $orderInfo doesn't
        ];

        /** @var ModifierInterface $modifier */
        foreach ($this->modifiersPool->getModifiersInstances() as $modifier) {
            $data = $modifier->modifyData($data);
        }
        return $data;
    }

Short description of the code: Order IDs are stored in the registry, a foreach() loop loops over every order ID and loads the order objects for those IDs, order data is stored in the $orderInfo array, which should be used to provide data to the grid.

Answer 1

I figured it out! The problem was that I was using Registry to pass the order IDs from my controller to the data provider.
Using Magento\Framework\App\Request\DataPersistor instead to pass the data is a working solution.
You can set the order ID array in the controller with $this->_dataPersistor->set("orderids", $orderIds);
And fetch them in the data provider with $orderIds = $this->_dataPersistor->get("orderids");