Percentage Coupon on Bundle

It’s a great plugin, but I run into an issue with coupon. The coupon is configured 20% off but only applicable to the bundles. When a customer applies the coupon, the discount is already $0.

The same issue was also reported 8 months ago, but the reply was incorrect.

The issue is due to the fact that the price of any bundle is always $0, then coupon discount is calculated as $0.

Please advise!