When importing orders with both the fulfillment status and fulfillment service the order may be marked fulfilled but have an unfulfilled label under the "Order details" title.

This will happen if you add a custom fulfillment service without adding the fulfillment service to your store. By default Shopify allows you to add the following values for a fulfillment service; "manual" or the name of the provider. eg: "amazon", "shipwire", etc. If you want to add a custom fulfillment service but don't want to add the service to your Shopify store you should set the value to manual.

To add the fulfillment service to your Shopify store you should follow these directions https://help.shopify.com/manual/shipping/rates-and-methods/fulfillment-services/custom. Please note that by default Shopify will send an email to the email address associate with your custom fulfillment service on every import. So you'll want to turn this off before you do your import. If you decide to add a custom fulfillment service you will see fulfillment details in the Fulfillments section of the order page.