in Swift 1.26.7
There has been a change in the templata \Designs\Swift\eCom7\CartV2\Step\Helpers\VoucherForm.cshtml, that courses it always to return an errormessage if the Voucher code applied is a discount.
As you can see the discount is applied to the orderline, even though there is an errormessage under the voucher field.
in Swift 1.26.4 there was a test for this. "vouchersAppliedAsDiscounts".
After inserting this test in 1.26.7 it seems to work as expected.