Hi,
We finally were able to reproduce the problem. It actually happens only with you have the "checkout legacy" setting activated in the HikaShop configuration (and thus you're using the old checkout of HikaShop). We didn't had the problem as we were testing the issue with the new checkout mode.
I've added a patch to fix that.
Please download again the install package on our website and install it on yours and that should fix the problem.
