Virtual member conversion to real member

Virtual members ca be added temporarily to manage some expenses while the real member is not yet signed up to the app. However, I can not find a way of converting a virtual member to the real one once the real member is added to the group

I see the UI to do this in the app, but it currently does not work for me. I tap "link to real member" in the context menu from the virtual member, and tap the real member from the list, but nothing happens.