BuddyPress.org

My guess (and this is a long-shot) is that you cannot leave the field blank once you’ve entered something in there, but BuddyPress also won’t lock you into that screen if it is.

Otherwise users could find themselves in all sorts of redirect problems going from profile group to group.

I haven’t tried that part yet myself though.

If there’s 5 required fields on the page, and you fill in 4 of them, in my opinion it should still save the 4 you filled in.