Inventory Committment to Secondary Location

We are trying to get our inventory setup to default into the location with the most inventory.

• Commitment Method = 1 on item master and item branch
• Primary has no on hand balance
• Secondary has plenty of available inventory
• Soft commits are not included in the Availability Calculation

I've entered an order for the item, and I expected it to select the secondary location with sufficient available inventory to fill order in the location field.  But the location on the order is blank.  It's not until ship confirm that it makes me enter a valid location with sufficient available inventory.  Is that the way it is supposed to work, or should the secondary location  with the most available inventory be placed on the sales order?