The bug isn't a bug but rather you have a misconfigured Product ...

There are Products, Downloads and Virtual Products ...

You have made a Download that is also marked Virtual ...

This is causing the issue as the check on:
Product
Virtual
Download

Cannot count properly as you have more or less assigned 2 definitions to the same Product by doing this ...

Try turning Product is Virtual NO on one of your Downloads and then test this ...

Does it work better now?