Problem

Shopify orders are being assigned to the inccorrect shipping method.

Cause

The reason this occurs is that Linnworks requires a tag in the postal service methods to use when assigning a shipping method to an order.

Solution

Ensure that the tag for the postal service contains the correct code or title.

The tag for a shipping service can either the title or code of the shipping method and can be found in the order xml.
Right Click in open orders > View > Order XML > Shipping Lines > Shipping Line > Code / Title

Add this shipping code to the postal service method tag.