I just applied a discount on a customers bill using the Round button on payment screen, and the discount did not appear on the bill. The Discount % button is printing as expected. This is not a Ticket Template Issue and might be related to removing the Auto Round Up and Auto Round Down from the receipts:
It appears under Services section because Include Tax setting enabled for Rounding calculation. In the other words it gets calculated after tax calculation. (… and discount calculates before tax). All calculations before tax listed under Discounts section and calculations after tax listed under Services section. Naming might be confusing for some cases but I couldn’t find a better idea