Why can't guests in group registration see certain custom field questions?

Why can't guests in group registration see some custom field questions?

If you have group registration turned on and noticed that only group leader can see custom field questions while the guests (additional registrants) can't, it's probably because you haven't made the questions visible to guests.

Watch the video below to see how to make a custom field question (e.g: T-shirt size) visible to guests in group registration: