problem with private page loading only in Firefox

I’m trying to link to a private page from a public page.

I made the destination page (recent-paintings) private so it doesn’t show up in the menu. Problem is it only loads in Firefox,— in the other major browsers; chrome, safari, opera, IE it goes to the index page.

go to link: https://rossow-web.com/paintings/ -then- click on link ‘recent work’

notice it goes to URL https://rossow-web.com/recent-paintings/ where ‘recent work’ should be but instead displays the main index page. ….

try this in fire fox first to see the correct way… then try in the other browsers….

Any thoughts how I can fix this so it works in all browsers?

thanks in advance!
-roy-