Issue in Shipping Transactions when processing order lines which are set to Backorder using the APIs

We are following an inbound integration process triggered by Standard APIs to set the Sales Order line entries to Backorder (if there is no On-hand quantity available for the item in the inventory) and initiate the Shipping process for the Order line entries.

Below are the APIs we are using respectively to perform the above-mentioned activities.

1. To set the order line entries as backorder
   WSH_DELIVERIES_PUB.DELIVERY_ACTION(
   p_api_version_number => 1.0,
   p_init_msg_list => 'T',
   x_return_status => l_return_status,
   x_msg_count => l_msg_count,
   x_msg_data => l_msg_data,
   p_action_code => 'CONFIRM',