Possibility 1: line item fulfillment is turned off 

The first thing to confirm is whether your line item fulfillment setting in FetchApp is set to "Automatically Fulfill Line Items in Shopify". This can be found in your FetchApp account under "Settings" > "General Settings".

Possibility 2: Shopify locations issue

If you've confirmed that your Shopify line item fulfillment is on, we may need to set your location ID. Since the introduction of locations in Shopify, we have had reports that some merchants are not having their orders fulfilled in Shopify automatically. To fix this issue, please do the following:

  1. In the Shopify admin panels, go to "Settings" in the bottom left.
  2. Once on settings, click "locations".
  3. You will see one or more locations, one that is labeled "Shipping origin". 
  4. Click the "Shipping origin" location.
  5. The URL will look like so: https://yourshop.myshopify.com/admin/settings/locations/123456789
  6. Send the entire URL (or just the numerical ID at the end) to support@fetchapp.com

We are going to implement an automated solution for this, which we are currently testing.