Sales Invoice Discounts not working

I can't seem to get sales invoice discounts to work in our environment.

I've set up a new customer and gone to Sales --> Invoice Discounts. I've set up a discount for the customer of 15% with a minimum amount of 0.00 and no service charge.

I've gone over to Financial Management --> Setup --> Sales and Receivables Setup and have set "Discount Posting" to "Invoice Discounts" and checked the box for "Calc. Inv. Discount".

I've also gone to the Item's General Product Posting Group and verified that a Sales Inv. Disc. Account exists.

When I go to create an order and either F9 or Release it, a zoom on the order shows that the Invoice Discount Code was copied over to the Sales Header, The Invoice Discount Calculation shows '%', but the Invoice Discount Value is 0.

Has anyone seen this before?