Follow the below steps to generate 2D barcode labels for the shipments from a batch.
Edit the batch by clicking on the 3 dots on the batch.
Make sure the batch is FBA and enable the 2D barcode option on it.
Verify that the batch has the 2D barcode symbol appearing on the batch as shown in the picture below.
Enable the unified FBA and 2D box labels Quick setting and you should be able to print them as you go.
You should now be able to print the box labels as required.