How to handle legacy_fulfill_request for Fulfillment Orders

[Shipwire_Dev]

Hello @Shopify 

I am getting thousands of fulfillment orders (FOs) with the below data in response when I am making requests to /assigned_fulfillment_orders.json?assignment_status=fulfillment_requested

"outgoing_requests": [
                {
                    "message": null,
                    "request_options": {},
                    "sent_at": "2019-11-21T16:43:52+11:00",
                    "kind": "legacy_fulfill_request"
                }
            ],

And I am just accepting these FOs so, that I can get new FOs on 1st page when we call /assigned_fulfillment_orders.json?assignment_status=fulfillment_requested

However, I am not able to accept some FOs, and getting error as:

{
    "errors": [
        "Could not mark fulfillment as open."
    ]
}

Here is the request ID - X-Request-ID: eefdc670-18ce-4f48-af35-4cc95c4977ec

Can you please help??

Ideally, I should not get these FOs as these orders are very old and already settled, however, I did not find any documentation on why I should get these legacy orders having kind as legacy_fulfill_request from 2019.

OR is there documentation on why I am getting this and what are the best practices?

Thanks!

Note: I saw a similar question but it's not answered yet and it's reported to be happening on new FOs.