fulfillments.json API endpoint returns empty response when all permission are added

[Integration_BDU]

Hi all,

We are experiencing an issue with our shopify API integration that returns an empty response for the fulfillment.json API endpoint. I received a 200 success code for the method response however the information I want to update is not reflected on the site. 

All the API key scope permissions have been added as well. I have also tried using different API versions and a different endpoint like fulfillment_orders.json endpoint. However the result is the same. 

Did anyone come through a similar issue? If yes, would you be able share the solution?

Thanks