Trouble importing orders with Amasty extension

Question

I'm trying to use the Amasty order import/export plugin. I can get the data to validate, but on import it throws this error:

Uncaught Error: Call to a member function getAdditionalInformation() on null in
/public_html/vendor/magento/module-sales/Model/OrderRepository.php:189 Stack trace: #0
/public_html/vendor/magento/module-sales/Model/OrderRepository.php(224):
Magento\Sales\Model\OrderRepository->setPaymentAdditionalInfo() #1
/public_html/vendor/magento/framework/Interception/Interceptor.php(58):
Magento\Sales\Model\OrderRepository->getList() #2
/public_html/vendor/magento/framework/Interception/Interceptor.php(138):
Magento\Sales\Model\OrderRepository\Interceptor->___callParent() #3
/public_html/vendor/magento/framework/Interception/Interceptor.php(153):
Magento\Sales\Model\OrderRepository\Interceptor->Magento\Framework\Interception\{closure}() #4
/fnbeuuvknf/public_html/generated/code/Magento/Sale

When I check the DB, it adds a row with the correct data to the sales_order table, but doesn't add anything to the sales_order_grid table.

Based on this info, is there anything I'm missing?

Thanks