Why is the shipping_line node null when placing draft orders on Shopify?

[_vee]

During the creation of a draft order with one of the Shopify apps, when we select a service and proceed with updating the draft order. The shipping_line node in Shopify order JSON should be assigned with the values that are selected, but the shipping_line node is getting assigned with the value null... This is happening with only Shopify Integrated carriers, other carriers it is working fine... Any help with this would be appreciated.

[OlegArtisan]

We have exactly same issue and it started in November.

Bigger thread linked to the same issue is here: 

https://community.shopify.com/c/shopify-apps/shopify-post-draft-order-not-respecting-passed-shipping...