Global Section NOT Visible to Add In Editing

I have a Global section that I wish to add to all my pages. All pages have an ACF field named et_url. At present time, all (almost all) of the et_url fields are empty.

I have added the plugin, and placed visibility constraints for the section to this expression: function_exists(‘get_field’) && get_field(‘et_url’) && get_field(‘et_url’) !== ”

The problem is that when I go to add the section to the page in the editor, the global section doesn’t show up in “Add from Library” unless I take out the expression testing for value in “et_url”

This doesn’t seem like the kind of behavior one would want. Certainly not what I want. I need to be able to leave all the et_url fields blank/unfilled at this time, add the section to the page, have it NOT visible until such time as I fill in the field. I don’t think it should not show as an element to be added to the page in the editor. The visibility should be controlled as presenting to the visitor, not to the edtior.

What am I doing wrong? How can I get the behavior that I want?