Fantastic tool for publising hidden pages

I use this for marketing exclusive offers. I advertise at a local restaurant and say exclusive offer for patrons of this eatery. Follow the QR Code link to get the offer. URL goes to a child page for my Special Offers and Promos page. When creating the page I simply click a box to choose if the page is visible on desktop devices and again for mobile devices. For these I choose not visible and the page does not get listed in any navigation menu. Customer has to have the URL to get to page. It works great. Using on WP 4.5.14. Trying to use on another site for same purpose but not working on 4.9.5.