I have a discount item with an amount of 100. I'm wondering why it's not showing in Discount item.

It only reflects if you add a discount item in the order head. Is a dedicated field for that

thanks for the info but I don't really understand. Order Head ? The discount item are on the line

There's a Discount Item and Rate fields in the header and not transaction lines. If you can't see them, maybe they're hidden in the form.

I find that if we use a discount item (we use them for item promotions) where we take 20% of one item etc, then because it's an item it's applied before and included in the subtotal. If we use a "order discount" promotion then the discount from this shows in the "discount item" section of the summary. Item discount • Item 1 is sold for 10 • Discount item for 20% • Subtotal is now 8 Order discount • Item 1 is sold for 10 • Subtotal is 10 • Order discount is applied for 20% = -2 (shown in discount item in the summary section • Total is 8