Incorrect order discount amount when combining promotion

Description

Configure 2 discounts:

• Buy at least 1 item in Mens Shoes, get fixed price = 10 USD.
• Spend from 5 USD, get 5% order discount, except items under Mens Shoes.

In Quicksilver, add a men shoes and a women shirt to cart (see attached image), and it works properly without crash, but the order discount amount seems incorrect.

Expect: order discount amount = 0.3 USD
Actual: order discount amount = 0.5 USD

Note:

• precondition: remove all of default promotions in Quicksilver.
• when remove the exclude condition from the 2nd promotion => the order discount amount is calculated correctly ( = 0.8 USD)