OnionShare "Show QR Code" Buttons Not Working

I installed Whonix on VB, then followed instructions to install OnionShare on the Whonix Workstation. Everything in OnionShare works perfectly, except that when deploying a service (such as a website), the “Show QR Code” button does not work–which makes sharing links and private keys via (say) the Signal mobile app pretty awkward. By comparison, the “Show QR Code” button does work on my Kali Linux VM. (It also works on Tails.) I assume this is a bug, but I wonder if Whonix Workstation blocks popups by default. If so, is there a way to enable them?

There is no operating system wide popup blocker.

Can probably only be resolved as per: