Import scenario only updating the first line on the sales order

So we generate sales orders from the portal from customers. When this is triggered the sales order defaults to the main branch JHB. When doing this in acumatica it works fine as it looks at the customer default branch.

We then have a GI which lists those SO’s, and then run an import scenario to change the default branch to the customer default branch. This is triggered with a business event on a schedule.

The problem we have is that only the first line on the SO is changed and the rest of the lines stay the same.

In this case the customer’s default branch is CPT, but only changed the first line

Any suggestion would be great